I wouldn't object to a M:tG campaign setting. Anything that isn't pseudo-medieval would be welcome at this point.
Thing is, there isn't
one M:tG setting. There are something like 15-20 planes with major expansions set on them, plus numerous ones referenced in sets like Unstable, Planechase, Magic: Origins, and so on. We have Dominaria (which used to be the main one), Rabiah (Arabian Nights), Rath (Tempest block, absorbed into Dominaria), Mercadia, Mirrodin/New Phyrexia, Kamigawa, Ravnica, Lorwyn/Shadowmoor, Alara (which in turn is made up of five different "shards" that each miss two colors of mana), Zendikar, Innistrad, Theros, Tarkir, Kaladesh, Amonkhet, and Ixalan. There are certainly some commonalities between these settings, but also many, many differences. The elves of Ravnica are not the same as those of Lorwyn, and the goblins of Kamigawa are not the same as those of Mercadia.
And Wizards works through these settings at a tremendous pace, about two per year (although they mix in some returning ones as well - out of the planes listed above, Dominaria, Mirrodin, Ravnica, Zendikar, and Innistrad have had 2 or more blocks set there). That would make it hard to do a D&D/Magic crossover product that would stay relevant very long.