Furthermore, why are these more "grifty" than any other alternate covers? And really, I don't see the alternate covers as a grift: they're just an option for collector's who like shiny stuff.
This isn't early 90s Marvel comics, where they kept re-booting series at #1 with tons of alt covers with the implication that they'd be valuable someday. And almost none of them were, because so many were printed (think, X-Men #1 in 1991 I think). At least the WotC alt covers are actually limited editions that increase in value, for the most part.
Of course this sucks for folks such as myself, who missed out on the funky Xanathar's alt cover and don't want to spend $3-400 on ebay for it. But, alas, First World Problems.