D.K.
As a child of divorce, I have a different perspective. My mom didn't change her name, but my step brother was the only one in his home with his last name (stepmom's 3rd marriage, first one had 3 kids, second just the one and none with marrying my dad) anyway, it used to get him down so badly he'd come home from school crying (he's got a great race-car driver kind of name) and he'd say he wished his name was the same as his mom & my dad. I can totally see why he was upset, no one in the world was like him, I think with having changed so much, having the same last name might help with adapting to the new life together.
D.