2-D Mario games are bare minimum platform experiences because they started with a formula that was extremely limited by memory. So essentially you have an entire series of 2-D platformers based around minimal platforming concepts, literally a few mechanics that rotate in and out of the same conceptual designs.

Saying that the 2-D mario games are good nowadays is just an impossible task because of the games you have to compare them to. Making an argument for old games because they are old and were limited by their hardware doesn't suddenly make them "good" games. If you want to talk about a good platformer, have a look at something that has stood the test of time due to its mechanics not its novelty. Super Metroid, Castlevania, World of Illusion Starring Mickey Mouse and Donald Duck.

No one looks at a 2-D mario game and goes, wow this is oozing with atmosphere. Wow this game is innovative. If you found 2-D Mario game rewarding you probably find a lot of very simplistic gaming concepts entertaining as well, it's no one's fault that the games are not good, but we probably can do better as gamers to not dote them as though they were preferential masterpieces.
Just my opinion, dont @ me