I think it may be because you've spent much more time in the older games, so that design is 'right' to you.
Also, with the theme of Mario Odyssey being different worlds/areas getting mixed up, Odyssey doesn't really have a single unifying theme Other than, 'hats, moustaches and googly eyes'. Unlike say, Super Mario Sunshine, which almost had the opposite problem. Odyssey is almost like a stream-of-consciousness of a ton of great ideas for a Mario game, all mushed up onto one disc cartridge. And I LOVE it.
3D World is masterpiece-level design and style though. The main thing I hate about it is the way you need a bit of time to accelerate to full speed. And then when you do, the farty sound effect when you go from walking to running.