mementomori: Thing is, when someone dresses "rebellious", according to me at least, they do care about people's opinions. Just as people who dress very conventionally whilst they don't like the look are making efforts to conform, those rebels are often making efforts to go against society's expectations. A punk with a mohawk may like the punk look, but those 30-centimeter spikes would probably not be so extreme in that individual if not for the will to rebel. It's possible that it would, but I believe the number of people with very non-conforming looks is lower than the number of people who would go that extreme "normally".
Anyway, my point is: in most people's life, being viewed as respectable and mature people at first glance (afterwards it could change for the better or the worse, but personally, I would be too afraid of a punk with chains and aggressive-looking stud bracelets to get to know them more deeply under normal circumstances... anyway, talking about first impression)...
So, yeah. Giving a good first impression and looking more mature and reliable will, for most people, directly or indirectly make them happier. Whether the happiness from the look or from that is greater depends on the individual, of course, but I believe toning down a style as you get older is a good compromise.
It's just that as people grow up, they're expected to change, to become more mature. And to express that maturity outwardly. And well, as for the comparison with transitioning... I would tend to believe that normally, gender identity is a bigger issue, probably worth more sacrifices, compared to whether your look is extreme enough in your opinion.
Ah, uhm. I'm not going to comment on that woman's age / look ratio because my opinion is biased by the fact I think she looked and still does look silly. I don't know who she is but she looks famous, so I hope I'm not stoned or anything, but I mean, when you view something as horrible (or wonderful for that matter), it's hard to judge changes.
Anyway, I don't think I have all the wisdom in the universe or anything, and I might be wrong, but I still believe that whilst boring, perhaps, my views make sense.