They've worked really hard for years so I wouldn't say their company has exactly steered them wrong in that sense even if it's possibly exploitative. >.> But they did manage to have a few consecutive hits like last year that were really popular with the Korean public, so I don't know why you don't think they're reasonably popular? I'm not sure they've really gone head-to-head with 2ne1 or snsd, though.
I dislike the line distribution (boram and qri have had next to nothing since igcboy, I think), but I'm not sure that's something the korean public generally cares about, since the three (or four?) most recognizable/popular members always get a decent amount of lines/exposure.
I personally dislike 1) the song production, particularly how they are (I assume) directed to sing, 2) a lot of the songs themselves, imo they're bland/repetitive and don't do anything for me, and 3) how rarely their lives are worth watching (I think the cry cry and, what, lovey dovey promotions were some kind of exception for them). 1&2 are my personal opinion but I think a significant number of kpop fans dislike that you can barely tell the girls' voices apart in the studio recordings. 3 is pretty widely acknowledged as far as I know, though. But I think this is more the international opinion than the korean opinion... unless Day By Day hasn't been doing well? It's only been out a week.
(One other thing, I guess, is that their debut was poorly received, from wiki: Their debut was looked upon negatively by webpostings, where people stated that it was lipsynched and commented that it seemed like an "elementary school" performance. This was in spite of a lot of anticipation for this group... in contrast, I believe that WG, SNSD, and Kara all debuted v strongly (back in 2007), as well as 2ne1. Even so, to my understanding, SNSD wasn't an overnight success either... until WG cleared the stage for them by going to the USA lololol. And of course, Kara's first album did not do well, and they reshuffled their members and changed their sound/image.)