Re: I can't help thinking that,
ADE is indeed a massive heap of unpleasant smelly stuff - and in particular on the Mac, where (unless they've updated it lately) you couldn't actually authorise a reader. So, I had to boot up Windows to authorise my old Sony.
Once that's done, Mac users then get lumbered with ADE when a new book is downloaded, as it opens the ACSM file and grabs the epub from wherever, before delving into Calibre to find the file and them send it over to the device via USB.
Small wonder, with all that dicking around, that many less technical people say "sod it" to the theoretical ability to buy books from anywhere, and choose a reader that has a store built in. At least, with the Kobo, you can enter your ADE credentials on the device, which solves that horrible nightmare.
I wish someone would do a sort of 'white label' ebook store specifically so that independent bookshops could sell things that way. And perhaps offer the value-added services of a) allowing people to pay cash for ebooks and b) copying them onto old Mrs Higgins' reader for her.
As others will be keen to point out, you can in theory convert books and get them on to either of these devices using Calibre. If you simply want to buy from any store and get a broadly compatible book, then in the real world you're presently talking about EPUB (with ADE if it has DRM), which means the least fuss solution is the Kobo reader, or any other that supports those two natively.
My collection presently has books bought from Waterstones, Kobo, Sony, WH Smiths, Amazon and probably a few other places. So in practise, the world while certainly not sane, is perhaps not as completely lunatic as you might imagine