Hey if you like Hatsune Miku, that's great. Their fine rhythm games but you gotta understand why fans of a company won't be thrilled about this being the only thing coming west?
But that would mean you'd have to actually like SEGA games.
I'm pretty sure we would have gotten the same complain in the Dreamcast era of Phantasy Star Online stayed in Japan and only Space Channel 5 was brought over...
Who said anything about localization? We don't know if this new game will be brought over, it could even be an arcade only game.
And really, there's nothing wrong with more Miku. The effort it'd take to localize something like Miku is a small fraction of the effort it'd take to localize PSO2, so it's not like it's preventing PSO2 from getting localized at all. Really the massive amount of content they'd have to localize, the huge updates, the servers, the risk of there not being a lasting community, all of the licensed stuff in the Japanese updates, and how late Sega is with localizing are each likely bigger factors into it not getting localized.
Oh, and there are fans of the company who are excited to get more Miku. Of course there are people who wouldn't be interested, but that argument could be made for any game Sega could localize, including PSO2.