It's one of those wonderful ironies of which life is made that everyone wants to be understood but few people seem to want to understand. Well wonderful for a given value of wonderful and also possibly not absolutely everyone, but hush, it was a good opening sentence for what is quite likely to turn into a meandering ramble of a blog post.
It's a stereotypical teenage thing to pout, declare that their parents don't understand and storm off to their bedroom, and it's seen as a sign or immaturity. Trouble with that is that they're probably right, or at least partially right. Right because whatever their parents might remember about their teenage years the specifics of their child's situation are going to be somewhat different, right because in some significant ways the world is a very different place than it was a generation ago, but mostly right because as adults we tend to have a very selective memory about what we were like when we were younger (personally I try not to remember anything that happened to me before I was thirty, it's just better that way). In any case the desire to be understood is hardly restricted to adolescence, in fact the stereotypical response is to point out that the teenager doesn't understand their parents (and why they might be concerned about a particular behavior for example), for some reason this is seen as a superior argument, rather than, you know, exactly the same argument. In either case the basis of the argument is 'you don't understand why I'm doing this, therefore your opinion is wrong' which is rather shaky logic.
Almost exactly the opposite attitude is in play when people say 'I don't understand how anyone can do that.' where 'that' can be anything from 'commit genocide' to 'go out in public without make-up'. The underlying logic here is 'I can't understand that, therefore it must be wrong'. Of the two attitudes I find this one more worrying, not for itself but for the corollary whereby people don't want to understand someone they dislike (or a group of people they dislike) because it might make them agree with them, or even become them, it's kind of silly when you think about it seeing as understanding how some historical bastard got to be that way might well help you avoid falling into the same kind of thinking yourself, but it happens, I've been guilty of it myself from time to time.
The thing is it cannot possibly be true that not understanding someone's point of view can both validate and invalidate your own opinion, and as you may have gathered from my comments so far I tend towards the opinion that neither is true and that understanding another person's point of view merely means that you understand their point of view and can agree with or disagree with it from a position of knowledge rather than ignorance. But learning to understand other people takes time and effort so why bother? Well I bother because I'd write really crappy antagonists if I didn't try and understand the darker side of human nature, wouldn't do much for my protagonists either really, given that I have a fondness for antiheroes, also I find it endlessly fascinating, but mostly, I figure that if I want people to understand me then it's only fair that I should put in the work on the other side of the ledger.