Judging compared to old Mario is a little pointless as they seem to be separated not just by 25 years but also the entire approach, plus old Mario was just another plat-former that gained its popularity from being the best on a well selling system, it not really anything special and never was.
By old Mario, you mean Super Mario Brothers? Oh, it was revolutionary AND special. I think due to its age you're forgetting how early in platformer history, especially of the side-scrolling variation, it actually came out. It had a rudimentary story behind it, which kinda started with Donkey Kong, power ups, smooth scrolling, differently themed worlds, epic fusion of gameplay and music, secrets, boss battles, precise movement control - we take some of this stuff for granted these days and don't see it anymore. Yes, there were platformers before and some of them had ELEMENTS Mario brought together but SMB was the game that truly introduced "new generation" platformers that have remained unchanged at their core ever since.
It's just like with RTSes - there were some games having elements of the modern RTS before Dune 2 but it was THAT game that defined the genre as we know it today.