I still have my ex-h name on my passport and I've remarried since then.
It's my (first) child's name and I kept it because it made travelling abroad easier. It would have upset my child at the time too.
Child probably thinks it's odd now, but I just can't be bothered to change it because it'd be a hassle.
I can't stand the guy, but it's just a passport so I don't bother doing anything about it.
I don't think names are completely irrelevant though as I won't take my current husband's name. But that's more to do with how happy I was to be back to myself again after the divorce. I'm just not willing to change it again.
Now I think of it, my whole situation seems very contradictory.
I'm unsure how either of the wives my ex has since had feel about me keeping the name, if they know. I don't think I care very much, it's not about them, or my ex, or my current husband, it's my name so the only relevant thing is my own mixed up contradictory feelings about it.
My name, my child, my identity, my feelings, my choice. Doesn't have to make sense to anyone else.