FINALLY! I'm so glad someone agrees. Mario Galaxy 2 was the most disappointing Mario game I've ever played. It seriously pisses me off that Nintendo made it. The story was literally a dumbed down retelling of the first game for the most part, it revisted a lot of ideas from the first game, and in general just felt like a more linear, watered down version of the first game. That's the opposite of what a 3D Mario title should be, but then I guess it's what I should have expected just by looking at the title of the game, the same as the last game, but with a 2 on the end.
Seriously, every game in the mainline 3D console Mario franchise has been revolutionary except this one. Super Mario 64 created the hubworld and brought Mario to 3D. Super Mario Sunshine had unique mechanics provided by F.L.U.D.D. and showed that Mario games could provide variety in the levels without resorting to "grass world, desert world, water world, lava world, ice world, etc.", not to mention it actually had somewhat of a story aside from "the princess is gone, go through levels and you'll find her eventually." Rather than go through the Mushroom Kingdom again breaking bricks and stomping enemies, you were actually helping to fix the destruction Bowser caused and got to see the effects of your help. Then Super Mario Galaxy came and made you rethink platforming altogether with its gravity mechanics, and allowed for limitless level variety, creating all sorts of bizarre worlds. It also had a vaguely interesting story in terms of discovering Rosalina's past, bringing an interesting new character to the franchise that deserves all the love she gets from fans.
Then Galaxy 2 comes along, and it's exactly what the title says, more of Galaxy. Except now the levels are more linear, simpler, and the story is a dumbed down version of the last one, as if a Mario game needed its story dumbed down. The hub world was completely unecessary, providing nothing more than a place to rest between levels. Seriously the most uninteresting and pointless hub world in the series. Where as every 3D Mario before it was a delight to complete 100%, this was a chore, no two ways about it. I HATE it. I'll acknowledge that it's a good game, I'll even acknowledge they made better use of the gravity mechanics at times. But I hate that this is a separate Mario game. They could have released the levels individually as DLC for Galaxy 1 and I wouldn't have hated it. That would've been awesome and would've made me buy it all as it came out, instead of borrowing it from a friend after the Wii U was already out. Imagine if they'd released a bunch of level packs each containing a world worth of levels, and it was all accessible from the hub world of Galaxy 1? How cool would that have been? I dunno, I still think I would've been pissed at how linear the levels are, but I would've excused it because Nintendo hadn't tried to pass it off as the next mainline 3D Mario.
Seriously, if Nintendo makes Super Mario Galaxy 3, I will never forgive them. I'll ignore the damn thing and hope that it flops. The next game needs to be a completely fresh Mario game with a new theme, new mechanics, and new worlds to explore. It should be as revolutionary as its predecessors, and Super Mario Galaxy 3 could never accomplish something like that.