Most avid DDR players already knew about the difficulty being pretty simple, you can tell from the screens Nintendo has released. As a DDR player, I'm glad this exists so more people get into the series. DDR is one of those games that just isn't fun on the lower levels after you've been playing for awhile. Playing on Light Mode is boring as hell when you can do Heavy Mode.
Like that Very Hard mode video from Jeux France would be like a 6 or 7 on the medium setting for the regular DDR games. If that's as far as it can go, then I'm going to have to pass. But I might pick it up as a gift for people I'm trying to get into DDR. I've been able to convince three friends to play already, and they became addicted within a few songs. Hopefully I can do it for more people with Mario Mix. People always love DDR, you just got to get them on the stage. Everyone is worried about not being good at it, but nobody started out doing those hard songs. Get up there and dance, fool!
I'll agree that after a certain point DDR become more about endurance than anything. I can read pretty much any song, but that doesn't mean I can do it, physical endurance is the only thing holding me back at this point. Which is kinda sad since I ran track in high school...