British philosopher Roger Scruton has an interesting passage on the coinherence of sentimentality and banality near the conclusion of his book The Aesthetics of Music. In this section he delivers value judgments not only on different musical forms but also on the audiences who enjoy and make use of them. What he says here spirals out beyond questions of music appreciation and into thornier existential matters such as interpersonal relationships and authenticity in a way that’s rather horrifying to consider. After analytically unpacking what this word “sentimental” means he denounces the vice he has uncovered.
This section exposed the sinfulness of my own bent towards sentimentality. I’ve been diagnosed as overly sentimental plenty of times and I’ve consistently resisted the charge with some fieriness, never quite understanding what that word could mean aside from “having an inappropriate amount of emotion.” What would count as an “inappropriate” amount of emotion? I always detected a whiff of supercilious detachment in the accusation. This passage, however, came to me like Nathan and solemnly intoned, “You are the man.” Just like that: undone.
I can’t begin to recall how often I’ve played one certain song a dozen times or more to repeatedly dredge up the same artificial feeling. In doing this I was engineering a pre-assembled emotional experience, continually reproducing this one “feeling” and keeping it ready-at-hand, a simulation of genuine feeling I could enter into at any moment without any commitment on my part. And it isn’t only music I use to this end: I’ve often used movies to effect the same sort of unconditioned, pre-packaged “feelings” and accordingly planned days and nights around the reliable emotional fix they would provide once I hit play. More sinisterly, though, is the truth that I’ve regularly done the same thing with people, exploiting relationships to get whatever dosage of “love” and “encouragement” I can obtain with the minimum of personal involvement and engagement on my part. My emotional life often has more in common with consumerist impulse than the experience of being a creature in the image of God.
Scruton’s exposition of sentimentality applies just as readily to our addiction to social media. His indictment of our mercenary approach to emotion (getting them “on the cheap”, he charges) and our inclination to manufacture personas in order to reap these secondhand emotions echoes (among others) Sherry Turkle’s conclusions in her book Alone Together: Why We Expect More from Technology and Less from Each Other. The most alluring things about Facebook and other social media is their free offer of two illusions: control and companionship. The attempt to wring as much out of companionship as possible through disingenuous shows of “connection” dovetails perfectly with the self-serving duplicity behind sentimentality. The superficiality of both “feeling” and “connection” Scruton denounces here lies at the very heart of our culture’s mania for social media. Sentimentality neatly camouflages our withdrawal from others, and under the sign of connection we retreat further into ourselves. Here’s Scruton’s indictment of all these counterfeits:
Just as it would be a mistake to define ‘sad’ as applied to music simply in terms of musical qualities, so would it be a mistake to define sentimentality in purely musical terms. In describing a piece of music as sad or sentimental I am using a predicate which, in its primary occurrence, applies to people. It is this primary use that must be defined.
In one of the few serious attempts by a philosopher to analyse sentimentality, Michael Tanner outlines four characteristics, as he sees them, of sentimental people: (1) they respond with extreme readiness to stimuli; (2) they appear to be pained, but actually enjoy their pangs; (3) they respond with equal violence to disparate stimuli at an amazing pace; (4) they avoid following up their responses with appropriate actions. It is characteristic of a sentimental person to respond with gushing emotion to a stranger’s misfortune, but to do nothing to remedy the stranger’s lot, moving on at once to the next object of emotion with an inner serenity that is only lightly perturbed by the superficial storms.
There is a recognisable syndrome captured by those four characteristics, to which we can add: (5) sentimental people respond more warmly to strangers than to those who are close to them, and are more heatedly concerned by abstract issues which demand no personal sacrifice, than by concrete obligations that cost time and energy to fulfil. (Dickens is a master at portraying this characteristic, perhaps because it was one that he shared.) Tanner offers, as a diagnosis, the suggestion (taken from Wilde) that sentimental people are attempting to have their emotions ‘on the cheap’; by which he means, having the pleasure of an active emotional life, without the cost of it. But what is the cost? Tanner does not explicitly say; and perhaps there is no general answer- the cost varying from emotion to emotion, and circumstance to circumstance. The cost of love, for example, includes all of the following: the trouble of caring for another, of anticipating and satisfying his desires; the pain of jealousy, when his love declines or wavers; the agony of grief should he leave or die. Far easier to fill one’s world with those casual affections which can be turned on and off at will, and to live du cote de Guermantes , where real sacrifices are displaced by petits soins. 
But that suggests another, and deeper, description of what the sentimentalist is up to. He is not so much feeling something as avoiding it. He is not feeling what he pretends to feel, and he prefers to pretend, for the pretence is deeply motivated. Sentimental emotions are artefacts: they are designed to cast credit on the one who claims them. The sentimentalist is courting admiration and sympathy. He wishes others to credit him with a warm heart and generous feelings; but he does not wish to pay the price that those things demand. That is why there is sentimental love, sentimental indignation, sentimental grief and sympathy; but not sentimental malice, spite, envy or depression, since these are feelings which no-one admires.
Sentimentality, so described, is a vice. Not only does it place someone at a distance from reality; it also involves an overevaluation of the self at the cost of others. The other person enters the orbit of the sentimentalist as an excuse for emotion, rather than an object of it. The other is deprived of his objectivity as a person, and absorbed into the subjectivity of the sentimentalist. The other becomes, in a very real sense, a means to emotion, rather than an end in himself. Although Kant tried to banish the emotions from their central place in the moral life, it is far easier to understand his great injunction, to treat others as ends and never as means only, if we restore emotions to their rightful place in our existence. For then we may recognize the distinction between the one who uses others to feed his own emotional fires, and the one who is open to the reality of other people, and as a result loves and hates, grieves and pities not for the sake of feeling some pleasurable simulacrum of those things, but purely for the other’s sake, and because these emotions are called forth irresistibly by the reality to which he responds. That is what it is, to treat another as an end in himself: and the cost of true morality is the cost of responding in such a way.
The sentimentalist is therefore a paradigm immoralist. His carefree existence is not a happy one: for it lacks the essential ingredients- love and friendship- on which happiness depends. The sentimental friend is not a friend; indeed, he is a danger to others. His instinct is to facilitate tragedy, in order to bathe in easy sympathy; to stimulate love, in order to pretend to love in return, while always reserving his heart and mind, and calculating to his own advantage. He enters human relations by seduction, and leaves them by betrayal. 
 The reference is to the third novel in Proust’s In Search of Lost Time.
 “Little cares”, or “trinkets”; making a fuss.
 Roger Scruton, The Aesthetics of Music (Oxford: Oxford University Press, 1997), pp. 485-487