(Change in bolding mine).
I'm sorry, since when has changing one's name NOT been accepted? Heck, it's pretty much expected when a woman gets married, and those who choose to keep their names can expect a certain amount of flack from the same folks who are liable to give people grief for not having children.
Hahaha. As a woman who kept her own name in marriage and never had kids, there is some truth in this.
And when men do choose to change their names, whether for marriage or some other reason, they often face more hurdles (this seems like gender discrimination). The name change paperwork for women who are getting married is relatively easy, but it takes more effort to change one's name for other reason. And transgender people do have legal trouble changing their first names to match their gender in many states and countries.
Still, there have long been legal options for changing one's name legally in western countries, as well as for having legally recognized pen names or stage names that are different from one's true legal name. Maybe one could have a "stage age"? I'm sure that would be popular for actors.
I don't think age is the same kind of thing as one's name or gender identity. It isn't really at the core of one's personal identity in the same way, as everyone gets older as they live. If one couldn't evolve their own age self-perception, we'd all still think of ourselves as tiny kids. Mind you, there is a point where one's self perception starts to lag behind the actuality. This manifests when I look in the mirror and think, "Who's that older woman? Oh, right, it's me." If he experiences that periodically, I doubt he's alone or that it's a basis for changing one's legal birth date on their birth certificate or something.