Well it's kinda what you're used to you know. You watch anime for a few years, you associate anime looking characters with japanese sounding voices, seeing anime characterd speak english just feels wrong. Ever travelled to europe and watched holywood movies dubbed in french/german/italian/spanish/whatever? I'd assume you'd find it weird too. I watch all my american/english shit with english language too.
I don't find it as annoying when it's a realistic looking game, like say Dark Souls or Resident Evil or whatever, because that doesn't look bad, but seeing the typical mascot character or the little girl or whatever other trope character they went with that's been done in every anime in the past 20years and then hear them speak in some weird high pitch english that tries to sound like the japanese original but end up just sounding creepy/weird, shit's just annoys me. Doesn't help that a lot of the english dubs also sound really bad to me, like they can't act for shit. Even what people call "good" dubs I find irritating.
So yeah, mostly it's just the disconnect between an anime character and speaking english, just doesn't make sense to me. If the style is more cartoony, works fine, but if it's pure japanese weeb shit, I hate having to listen to english voices on it. And Persona is definitely anime, like super generic anime.