Ok, I've watched the whole video and I'm gonna comment it:
1) "It should be called Super Mario Galaxy More"
(I'm gonna ignore NSMB series, ok?)
Nintendo doesn't make direct sequels to a mainline Mario Game since... SMB3, I guess?
Even Super Mario World have a different name because it does have a different approach (it's more focused on exploration than in platforming than SMB3).
Majora's Mask is not OoT 2, is a different game reusing assets.
So, I think Super Mario Galaxy 2 tells to me exactly what we are going to expect: more Super Mario Galaxy. I don't think changing the name would make any difference.
2) The atmosphere is better in SMG1
Yeah, that is undeniable. But that hub world is part of that and is TERRIBLY designed and it is by far the worst hub world in the Mario Series.
It's awful to navigate (specially to the upper areas), it's confusing when the comets appears, you have to go back and forth all the time... like, even when the game launched I hated how much time I spent searching for stuff/getting into the levels. It is a slog and it's not even fun because Mario's movement in Galaxy is not as great as in SM64 and Sunshine.
And I still love Peach's Castle and Delphino Island (even if that I don't like SMS nowadays)
I also didn't think that having a giant number in the center of the ship is something that builds up a lot of expectation.
I also think he values things that I can ignore in a Mario game.
Like, FFX-2 have an AMAZING combat in a game that I don't like the story/structure at all and that's terrible because what I expect from a JRPG is story, narrative, etc. The combat is important, not the MAIN focus. So, of course I prefer FFX even if I love FFX-2 combat.
For me, it's the oposite in Mario games, I expect levels to be FUN and to get to them really fast.
I think all that "atmosphere" sometimes gets in the way of the part that I really really want from a Mario game.
With all that said: his argument is perfect to talk about DKC series. I really think DKCR/TF atmosphere is way way way worse and DKC/DKC2/DKC3, and even if I think Tropical Freeze the best game of all, DKC2 is unique and special in a way that TF will never be.
Fun fact: I reviewed DKCR for a Nintendo magazine here in Brazil and it was difficult to give a score because the game is great but is not what I've wanted (in the end, I think I was fair).
3) "I love having time to breath"
Ok, I don't. I like intense games.
Yeah, I do like slower paced levels SOMETIMES but I don't miss it when we don't have. SMB3 is my favorite, at all.
That said: WTF he used that pengiun level as a good example, it is sooooo boring. Also I don't like that Spring Mario level either.
(and yes, I think most levels in SMG are great but SMG2 is another level)
4) I respect his opinion
I agree that Miyamoto's philosophy is not good all the time and it was good to see a Mario game going next level in terms of narrative.
But it is SO hard do find that spot that the game have a good narrative and it's not terribly cringe that I really can live without any development.
Oh god, remember what we saw in Super Mario Sunshine? All those terrible cutscenes?
Think about Sonic games too.
Yeah, that's not an excuse for not trying, and they really nailed in SMG. But when I think about SMG I never think about the supernova at the ending or Rosalina's storybook. I think about great levels and great songs - something we also have in SMG2.
Oh and he praised Bowser levels for trying to be more "traditional" pltaforming challenge. Yeah, I love them for this. But this concept is not new in 3D Mario, is actually an evolution of Bowser's levels in SM64 - they also share the same song ;-)
TLDR; I understand his points but I don't care about most of them.