ME2 was definitely treading water, and I think it was smart to focus on the characters, but yeah, you're absolutely right. I adored ME2, but I think it's a good example of why aspiring to make a trilogy for the sake of having a trilogy is sorta misguided. You learn about the bigger threat in the first story, you resolve the threat in the third story, unless all three stories are designed to be self-contained, there's not a whole lot of avenues for a second story beyond additional setup.

I feel like a lot of movie trilogies have the problem of making the second and third stories one giant sequel instead of two distinct stories. Using two (admittedly kinda bad) examples, Pirates 2 and Matrix 2 are just "part 1" of the story of their third movies.

I just wish franchises aspired to tell one grander story, regardless of how many installments naturally tell that story (assuming they're not designed to be distinct, standalone stories), instead of shooting for 3 just because it's a nice number. The first two InFAMOUS games kinda nailed it. The overarching threat of the first story is resolved in that story, but it also serves as the jumping off point of a bigger story, which is resolved in the second game. Trying to make Cole's story a trilogy would've been to the detriment of InFAMOUS 2.

Sorry, this was kinda apropos of nothing, and I still love ME2, you just reminded me of why trilogies sorta bug me.