...This game was YEARS before the 918 incident, though...? It was also only the second game, not counting arcadem@s... So it's not like they went from OFA/imas2 to SP or something. Calling it "cheap" or saying it's like an unfinished beta isn't really fair.
I think part of your problem with the game is that you're judging it based on OFA standards instead of 2008 idolmaster standards. SP is a relatively old game; the series is huge and almost a decade old now, but it was only a few years old when SP was announced. It was established but not nearly as huge a juggernaut as it is now.
I mean, if you don't like SP, you don't like it, but you should judge it on its own standards instead of 2015 standards.
if we're talking cuts in quality and an attempt to cash in, Shiny Festa kinda fits the bill... Nothing really new except the rhythm sections (which l4u had already done), done at the very tail end of the system's lifespan, and also some of the MVs are really lazy (like Shalala. They're literally just swaying back and forth for the entirety of the song. ;_;)
It's better than the Love Live Vita game, however. That literally looks like _I_ programmed it. But it was probably a complete cash grab so. (i still love the series tho)
Regarding DLC, SP had some awesome and cute outfits like Takane's Punkish Gothic and the wolf girl costume. But then you have... Like... That ugly plugsuit extend. I feel like they took quite a few gambles with the DLC and it paid off most of the time, but it also resulted in some really out-there stuff.
(I want them to go back to incorporating MASTER ARTIST songs as DLC ;_; Nemurihime and livE and Flower Girl, we hardly knew ye)