The looks don’t fit in with the rest of the game, at least the SNES tracks actually look really good because they completely remodelled them and kept just the layout of the original
Yeah remaking a SNES track would actually be more work than grabbing a map from Tour and doing a few tweaks to make it work in MK8. The SNES maps are actually interesting courses, like Donut Plains has an underwater bit, and the SNES Rainbow Road has thwomps that send shockwaves through the road. They're essentially brand new original courses aside from concept and general layout.