Y'know, I did some thinking about it and I figured out why even the quirk-less CG characters feel so bland. In main idolmaster games, the characters develop VERY slowly and realistically. You go through dozens of lessons and spend almost an entire year together before Yukiho gets over her shyness or Chihaya slowly starts to accept her brother's death.
But meanwhile in CG (ML is better with this) each character gets like twenty lines or so. You can't cram any closeness or intimacy into that. Some characters develop through mangas and extra cards, but could I tell you the first thing about Ranko's family situation? What Uzuki likes to do for fun? Rin's hopes and dreams? No. Not only that, what character arcs exist are very small and resolved in just a few cards. Kanako's disbelief that she can become an idol? Nah, taken care of once you fuse her. Maybe it will change with the anime... Hopefully.
This is a good point. I had noticed this myself in the past and it becomes even more obvious when you see how reduced 765 was. I'm thankful they started out in an arcade game and not a mobile game for starters.

It's also why I can't really comment on CG or ML. They just aren't very detailed at the moment and most if not all of them are designed to want the Producer. While it's true in the past idols have had feelings, it'd be interesting to see an idol who wants a strictly professional relationship. Chihaya has had moments where she rejects Producer, like telling him to stop his delusions in SP, but she's pretty fond of him as well even in SP.
But... Like... I still like CG for reasons I'm not sure of. It has that "something", and if you don't get that "something" then the games will be pretty crappy for you.
If you can't say why you like it or what that "something" is that's pretty troubling. I could go on about what I like in imas but that's off topic.
Also DS would have been really good if they made it a visual novel/light novel/manga (therefore eliminating the awful gameplay) and cut out Ryou's entire ridiculous ripped-right-from-a-bad-manga "IM A BOY BUT NO ONE KNOWS DUE TO INCREDIBLY CONTRIVED CIRCUMSTANCES" route. I feel like the only person who really dislikes Ryou tbh. Like... The only interesting part of him is his "secret". which has been done in 5000 awful harem mangas.
tl;dr cg is too fast-moving with character development but has a certain charm, ml's girls are good but the game is really gross and creepy, and eri and ai are great characters who need a better game someday
DS actually has three manga which are translated. I will not comment on how good the game is or not. I agree that Ryou is probably the weakest of the three DS and thanks to him we got Jupiter and SideM. Male idols aren't bad, but it's certainly not what I got into a
galge for. I did like Chihaya's appearance in DS, that bullying in that party commu was really rough however. One thing I liked about DS is they seemed to have good harmony.
Hibiki and Takane's reveal was nothing short of perfect for me. It was a great way to sell people on SP, and it tied into the story. Granted, these two characters had been planned since the beginning of the series, but time and effort was put into them. With CG, NBGI left it in the hands of fans to pick and decide based off of looks alone. We never even got to hear their voices. It's a good way to alienate a ton of fans, because they could see first hand the popularity contest between all these uninspired idols, and perhaps many didn't agree with them.
I just want developers to put work into what makes them money. It disgusts me when mobile crap becomes successful. It's cheap, it's lazy, and it's exploitative.
It doesn't fit with the points I made. I just never liked it because how they shoehorned in some shota character, and how Eri is forever trapped with those two lesser idols. It wasn't a very good game to begin with, really.
I agree the way Takane and Hibiki were introduced was great. A bit too great in fact considering they haven't been written as well since. I'm very disappointed with how they've been writing Takane in particular thus far. DS also wasn't so bad as they got plenty of focus while still including 765 and it gave us a perspective switch which we hadn't had since L4U.
I've actually heard that japanese fans were comparing idolmaster 2 to AKB before it's release thinking that the idols were being split into four groups. Funny enough CG reminds me more of it with the paid polls and voting who gets to do what next. Honestly I think it's bad for people being attached to a game just because one idol matches their niche. With vision 1 everyone got a route each game. With CG most of those girls won't even be voiced, let alone get a route one day.
ML is done by the anime staff, you know the ones who couldn't even write 765 properly. From what I've seen from ML it's like they're trying their hardest to be interesting but failing.
Honestly a lot of these idols just aren't interesting even at the concept stage. Of course when I mention that someone goes on about how 765 sucks and that I should be adoring every idol just because they're a part of idolmaster now.
I don't really mind the fan service really but that seems to be an unpopular opinion.
@animagic4u
As stated I did play both of these games for a fair amount of time.