Why the hate towards male idol characters and mainly mobage/GREE/mobile games in general?
I'm actually someone that likes all the different sub-series: main, CG, ML, and SideM. I'm particularly a fan of main + ML myself.
However, I'll have to mirror what Nayoril said. There's just too many. The series from 2010 all the way to now went from 13 main voiced idols to over 100. That's just voiced idols alone. A number of people just can't keep up with that high a number.
And going to Nayoril's second point, the amount of idols is difficult to fully develop all of them. Moreso in CG than ML and SM since contrary to popular belief, the latter two (especially ML) have story commus that give more insight on the characters. However, of course it's not nearly as much as 765Pro, which to be fair have had 10 years worth of development, games, and overall existence to be fleshed out while these spin-off characters have hardly had half that time. There's great potential, but these characters need to be in a console game for that potential to be realized by a larger number of people.
To go to DeviantProtagonist's point, it may be a vague and blunt answer, but that's another existing mindset. People have gotten so attached to 765Pro for the longest time, they can't see themselves be bothered to get attached to the spin-offs. Whether it be the large number of idols, the lack of development in comparison, the lack of a console game, not having their favorite idol, etc., some people can't be bothered to leave what they're most familiar and comfortable with.
Also, as games, I hear the mobile games aren't very good. Like, at all.