Yeah, this looks more like a official vs fan sub/bootleg type thing. Any ways, there is one main reason why I would want official English releases. I like having physical products. If I were to buy official DVDs, I would want them to have subtitles, practically none do as it. I've been tempted, but the price + no subs makes it sort of easy to be swayed. :/
As for the aesthetics of fan subs, fonts and special effects... Eh, I don't think they are enough to really warrant a reason to not want official releases. And as for fan subs stopping, a lot of anime gets fan subbed after it has been licensed. Hell, there are places that rip the official anime dvds.
I can sort of see what you mean by mainstream. Once anime gets dubbed, the fans it brings along scare me. But I doubt tokusatsu has too much of a chance of being that big, Power Rangers has had its affect on Americans. Even if there were official releases here, in the States, it'll probably always have a small following.