From Takashi Tezuka:
> “In the end we used the New Super Mario Bros. U system for all of the game styles. There was quite a lot of discussion about this within the team. Staff who had strong attachment to the original games expressed a strong desire to see implemented the same system they remembered. However, when players who are used to the modern Mario physics tried playing with the old physics, they found it much more difficult than they remembered."
People on reddit have done some pretty extensive breakdowns of the physics of different Mario versions vs. SMM: