Exactly.  It was never advertised as Mario Galaxy 3, and therefore undeserving of the hate piled on it by people who placed unnecessary expectations on it.  The people who understood it as a sequel to Super Mario 3D Land, which is the only thing it claimed to be in the first place, enjoyed it very much for it was.  Myself included.  

I honestly think I may prefer 3D World ever so slightly after doing most of what Odyssey has to offer. Even though I love true 3d Mario more than the hybrid of 3d land/world, 3D World is hugely underrated and I feel like Odyssey is already pretty overrated. I think 3D World offers more variety because all the levels make it feel less tedious than the dozen or so kingdoms do. Collecting the moons just isn't that varied in Odyssey after the main objective ones. Also, the multiplayer in 3d World remains a blast that is sorely missed in Odyssey's meh co-op mode.

3D world has the best local multiplayer I experienced. Sorry odyssey.

Liked both games (also liked 3D land on the 3ds) though obviously Odyssey is the more ambitious game. I do hope Nintendo make some kind of sequel or continuation to world/land in the future. Would prefer it to a new 2d mario anyway. I also kinda preferred the galaxy games so far but I should wait til I’m closer to 100% completion of Odyssey to be make an honest comparison (the fact that when previous games were released I had more time to kill might be hindering my judgement too)..

I think it was less a matter of it not being Galaxy 3 and more that people expected more from the first the first HD 3D Mario than just a 3DS game with a coat of paint.

And it wasn't a 3DS game with a coat of paint ..... As someone who has played both and 100% both, neither are close to being the same level of quality and ambition which is normal because one is on a handheld and the other is on an HD console. However, it doesn't mean they share an artstyle that they are games of the same quality...

It wasn't so much the art style, more the level design; both focused on small, simplistic courses without much in the way of discovery or sophistication.

Well I respect your opinion but I heavily disagree. 

But is a game with a lot of "flow" in the gameplay because of that, linearity has its advantages when done well and that game did it well, the lack of ambition was its biggest mistake but not the lack of quality.

I'm not saying it's not quality; it is a polished and enjoyable game. I simply feel that it doesn't quite have the imagination or depth to put it on the same God-like tier as Galaxy, 64, or Odyssey.