The main issue I have with the Mario64 design is that despite being the 3D evolution of a platformer there's not all that much platforming to speak of. There's a lot of running around, punching bad dudes, and climbing. Yeah, there's jumping, but I'm really not into these big, open worlds where you do more running around than anything else.
Both Galaxy games still do a lot of this, but I felt there was far less focus on big, open areas and more focus on getting to newer, smaller areas. Gravity jumps, riding vines, launched by stars, etc. There was a lot more jumping, a lot more platforming, and a lot less time spent in singular areas.
The worlds in Galaxy I disliked the most unsurprisingly were the bigger, open ones, like the two bee levels.
I dont really care about having this big open adventure world with cohesive movement between locations. I just want platforming. Lots of shit to jump on and lots of obsticles to navigate.
Thus, I prefer the tighter platforming of something like Galaxy 2, and hope Nintendo stick with that.