Not very deep yet!
Many people, mostly young ones, feel it's very important to keep up with the latest trends in social things such as clothes and the music they listen to publicly. Choices in these areas are largely based on whether something is new and whether the people they want to feel part of a group with have the same things, with it being best to have something at just the right stage of its becoming popular. Things such people find desirable rarely have much intrinsic quality that will endure; indeed, if something has intrinsic quality, it is much harder for it to be trendy, since it will be seen as staid or square.
A traditional psychosocial explanation is that young people want to feel they belong to a group, but feel they cannot join ``square'' (adult, sucess-oriented) social groups, so, to avoid feeling that they are failures, have to put on a play of rejecting squareness (because otherwise they would be acknowledging that it has successfully rejected them). To make up a social group that is not based on success and quality, they have to choose things that squares (acheiving adults) would not choose, and so cannot go for things of intrinsic quality as that would label them as wannabees.
Associated with this, perhaps, is the petty adolescent antisocialness (which they prefer to call rebelliousness): the wanting to do something that they can tell that people more successful than themselves would rather they didn't do, such as playing artless music loudly, and cycling the wrong way up one-way streets or cycling on the pavements... the ``you can't make me do it'' attitude of someone who has not taken any control of their own lives but is determined (or is it pre-determined?) not to let anyone else have control... the result of which, risibly, is that they do the opposite of what they perceive is wanted, and are actually quite controllable -- or at least very manipulable -- by giving them the impression that they should not do something. A shining example of this, reputedly commoner in the US than in the UK, is people resenting being required to wear a seatbelt... they would rather risk their lives than comply with someone else's wishes, even when that someone else is the general public amongst which they live.
This resentment of control or even influence from other people implies the people concerned wanting to be allowed to do exactly what they feel like... conversations with people I've found, for example, driving the wrong way up a one-way street, suggest that they resent the law, and regard its enforcement when it applies to them as being unfair (to quote: ``If you were a copper, you'd be bent'' -- that was for pointing out an unambiguous trangression of a clearly stated law! And yes, the car was a Ford Escort!).
Some say that this feeling you should be able to do whatever you like (sometimes systematized into anarchistic doctrines involving an assumption that everyone is basically responsible and altruistic) indicates that the people concerned have the pride of assuming they are right; I think it is much more plausible that they don't care what is right, only what suits them.