I'm a cis white dude. Default gender doesn't bother me in the slightest, but I always appreciate when a female is the default. As far as something like smash goes, though, I honesty think it's kinda pointless. Smash absolutely needs more female characters... but I don't really think avatar characters that are defaulted to being male (Villager, Robin, Corrin, Byleth, etc.) like I genuinely want female characters who are... well... genuinely female lmao. In other words characters that don't have the option to be male. Anything else doesn't feel genuine to me. Take your Byleth and shove it up your own I want Edelgard flag nabbit.
Gender options I always appreciate. Back in the day I had a blast making wacky characters in Saints Row 2/3, and being able to mix/match male and female clothes, hair, voices etc. was always very entertaining.
These days, I still really appreciate them. Not so much for making "wacky characters" but mainly for the fact that these non-binary options make a lot of difference to some people. I guess the same argument could be made that default gender matters to some people, too, but I just don't get why you wouldn't rather fight for a character that's blatantly female instead of just an avatar. Just because you see a lady on the screen by default for Byleth doesn't make the character any less of a male to me.
Maybe I'm just salty about Edelgard. Maybe my minor OCD would just get cranky over all of the avatars not having the similar default state. Maybe I think default gender is a lazy cop out for female representation when there's so many more fleshed our characters that would make splendid additions to the roster (LIKE FUCKING TWINTELLE). Actually, yeah. That's it. The last one. It feels lazy. It feels pandering. It feels like that's the option Nintendo would take if they wanna please those who are wanting more diverse representation, but still want to choose a character that wouldn't get people overly-salty for being a female or a not-too-well-known character.
Final tangent: I want Monster Hunter in smash. I'd love for the default gender to be female. More importantly, though, is the default armor she'd be wearing. 🤔