I understand your frustration with variants..
That said, I don't think most collectors are the "completists" you and I are. I suspect most only buy the cover they like the most or the one they think will be worth the most.
So while it may be annoying for that small set of 'completists', for the average consumer, its a huge bonus in that they can pick their favorite one...
They are also a necessity in this market for LCS'. Without those 1/25, 1/50, 1/100 books to augment their margins, they would have an even tougher time competing with all the other options available to consumers.
Knowing that, I suspect variants really lie at the feet of the distributors and LCS' who not only relish in those variants, but in all liklihood, request them specifically; blame does not lie with Marvel, et al., themselves.
That $1.25 an LCS pays Diamond for the 1/25 variant regularly sells for $15-$20; $13+ more than a cover-price book. That's a hell of a margin that shop owners just aren't going to get anywhere else. It's actually genius marketing and salesmanship, imho. You could argue that those variants are actually keeping a good number of LCS doors open that would have been shuttered without them.
just my $.02.