They've said as much, since Galaxy and pointed it out again in the lead up to 3d Land and 3d World. I mean Mario, as whole, has always been meant to be an all age, all skill level game, and that the approach SM64 took being so off putting to many who played 2d Mario was completely unexpected; and every 3d Mario up to this one has been attempt make a game that joins full 3d playing area with the broad appeal of 2d Mario.
This article is a good compilation of all the statements Nintendo's made about wanting to bring 3d Mario to the 2d Mario audience.
https://dromble.wordpress.com/2013/09/21/nintendos-frustrations-with-3d-mario/
Heck I'll be honest for years I was one of those 3d Mario is wird and strange and not really Mario to me Camp. I think its easy to forget how shocking SM64 could be for someone. I know my first encounter with it was nothing but confusion, and I've heard similar things from others. Here's my particular experience. The context was I didn't think I'd ever played any of SMB 2 USA, so I go up to this kiosk, at 9 or so and I bring with me an idea of what a Mario game from playing SMB, SMB3 SMW and the two Land games. So I'm at this kiosk and I look at this confusing controller and the d-pad isn't doing anything. I mange to figure out I have to use the strange stick thing in the middle, but right there I'm already sort of on edge I guess. Then I look at the game, which is in the courtyard, and where are the bottomless pits? And Enemies? And why are there no question mark blocks with power ups? I eventually made it to Bob-omb Battlefield and okay now there's things to do and Goombas. But still no question mark blocks , and the brick blocks look completely different and aren't floating, and Mario has a life bar? And where is the super Mushroom or fire flower?
And I walked away from that experience that what ever that game may say it was, it was not Mario. Now it took years but I did open up to it.