>>10318376Lego is a brand that usually has a strong, consistent aesthetic, even between very different themes, because the whole point is to be able to take the sets apart and put them together with other sets to make something new. You can put the space set with the cowboy set, and your astronauts with your cowboys, and it works. The Mario sets throw that completely out in favor of an electronic gimmick that acts as a vague notion that you are playing a half-baked implementation of a watered-down version of the games. These sets don't work with anything but each other. You can't have Mario walking around in a Lego City set without him looking like some kind of freakish monster terrorizing the people. You can't have Peach living among your other castle residents without a place set aside specifically for her.
The gimmick, itself, has notable flaws, too. You need Mario and crew to be powered on if you don't want them looking like they came out of a shitty creepypasta, which means maintaining their battery charge. Most of the smaller sets are usually useless without buying a more expensive starter set first, which not only can be confusing, but also means being forced to buy something you may have no interest in. These sets are designed entirely around their gimmick, and if you have no interest in the gimmick, you have no reason to buy the sets.
Essentially, they're Mario products first, Lego products second. You're not meant to use them with other Lego sets, and thus they lose most of the appeal of Lego. The Lego association is purely for marketing purposes. They live in their own isolated bubble, separate from everything else.