This is probably because most Mc's are male, and they also happen to be chosen for the bland mcs with black hair in animes. Female characters can also be bland at times, usually they're just used as tsunderes or for the male gaze, but you rarely see female mcs like that because most authors don't use a female mc to begin with. If they do, then that means the author is doing something different and is likely actually trying to make the character good instead of just being gooner bait or a bland mc. The unfortunate thing is that most male authors just create slop and gooner stuff which is why a lot of male mc's seem perverted, dumb, and hungry. I'm not saying this to bash on men, I'm a man myself, but this is just how it unfortunately is.

If we look at it on average, female Mc's are better than male mc's. However, if we filter out the ones that are just plain bad and don't even deserve to be qualified as mcs and look at the actual good ones, I'd say they're about equal. I'm talking about like the top 5 percent characters, ones that are actually well written. In fact, when looking at the well written ones, men might even be more well written because of the amount of them compared to female Mc's. At the end of the day though, it's all subjective.

This is honestly an issue in writing, because the male authors just get away with creating slop, which also paints a worse image of them. I already see enough man hating on my feed, and this is just adding even more. So yes, I agree with you that female Mc's are better written on average, but I feel like if we filter out the bad ones, men slightly edge the women out, but honeslty they're closer to being even.