Actually none of the games you mentioned are by NIS , they are published in America and Europe by NIS America but they aren't NIS games as such.
Last Rebellion is a Hitmaker Game.
Cross Edge was by Idea Factory and Compile Heart (NIS, Gust and Capcom just had a few cameo characters).
Trinity Universe seems to have primarily been Idea Factory (both Gust and NIS are mentioned as creators as well but since their are very obvious cameo NPCs from both of them and the battle system is a less brain breaking version of Cross Edges, its pretty obvious who was the primary developer. Especially since Agarest (Record of Agarest Wars or Agarest: Generation of War depending on where in the english speaking world your live has a very similar battle system to and its a Compile Heart & Idea Factory game that wasn't published by NIS).
Also the paid DLC for Cross Edge and Trinity Universe was mostly optional, with only a couple of exceptions (ie most of the DLC that added stuff that wasn't in the game was free, and most of the paid stuff was bribing your way to victory).
There were a few NIS games with "part of the full experience" DLC like Prinny, D2
HD, & D3 but those were usually fairly cheap on a per item basis and you wouldn't know you were missing them unless you knew about them so they aren't exactly game critical. D3 was a bit of an exception on both fronts the sheer quantity of the DLC made it expensive even though each item was pretty cheap and the patches that actually contained the data added a preview store so you would notice that stuff was missing.
Thats not to say their aren't problems with many of NIS America's releases, Hitmaker developed games tend to be as buggy as all get out, obvious betas and/or have some really poorly thought out design choices, for one, but its better to correctly attribute faults.
On a more personal note, am I the only one that thinks "rehash" and "churning" are ridiculously overused when it comes to criticising games particularly turn-based RPGs ? The things people tend to complain about being repeated tend to be the fundamentals of the genre or the differences from the genre that sets a company apart ie the things that people who actually buy these games buy them for. I for one don't want Action RPG in my Tactics game and find such "innovations" generally decrease the quality of games (Cross Edge for example suffers from not knowing if its a Turn-based RPG or an Action RPG) as the two don't mesh well since Turn-based RPGs tend to punish you severely for making wrong choices and Action RPGs tend to punish you for not having twitch reflexes. I don't want Disgaea 4 to play like a hideous hybrid of Warcraft III and Disgaea 3 in the name of innovation, I play Disgaea games because they are turn based RPGs.