Bird and Bear, I see your point, as I'm somewhat of a collector myself, and I like matching series. I have matching covers for the first editions of the Second Chronicles of Thomas Covenant, and the matching covers for the SF Book Club editions of the First Chronicles.
My Dark Tower collection is a mess, though. I once had the limited editions of Gunslinger and Drawing of the Three, but sold them during a time of financial crisis. I kept the limited edition of The Waste Lands, though. So I have the reissued trade paperbacks of Gunslinger and Drawing, the limited hardcover of Waste Lands, the first trade paperback of Wizard and Glass, and the hardcover of Wolves.
My Gap series is just as lame. I have the mass market pbs of the first two, the first edition of the third and the SF Book Club editions of the fourth and fifth. I don't know what happened to me. Brain glitch, I guess.
And of course, as you hint at, it isn't always the reader's fault, because the publishers are inconsistent and they keep changing the design as the years mount up between the publication of books. Already my Song of Ice and Fire hardcovers don't match. I'm being penalized just because I recognized greatness from the original printing of Game of Thrones back in 1996?

"I am, in short, a man on the edge of everything." - Dark Tower II, The Drawing of the Three