My main concern with digital copies is a common one: long-term playing. I've gone through 3 Super Nintendos over the last 20 years but I'm still able to play all the games I got back in the early 90s because I have the cartridges. If they had had digital releases back then, Nintendo at some point after the end of that console life cycle would stop supporting re-downloading to new systems and I would be SOL.
Eventually, my 3DS may not work anymore and that might be 10, 20 years from now. Mario games, even the lesser ones, especially lend themselves well to picking up again after years between playing them, so I will want to hold on to this game for decades to come. Therefore, I will buy tangible copies of most games.