I wonder if the more realistic levels with have more of a sound designey focus rather than traditional Mario jazz playing in the background.
I think it's more to do with Zelda being old news and Mario being a new announcement with a weird twist.
Something that I found sort of surprising to me was that the Super Mario Odyssey trailer on Youtube has the most views of the Switch related videos at almost 4 million and is currently #1 on trending, with the Zelda BOTW at second with 3.1 million views.
I would have expected Zelda to overtake Mario currently, but this speaks more the enduring legacy that Mario has made in the general public and I can expect that the Switch would move a lot of consoles when it comes out in the holiday.
I think it's more to do with Zelda being old news and Mario being a new announcement with a weird twist.