This is exactly what I've been doing and it works fine for me. Like you, I just buy from wherever sells.

By stopping downloads, they're obviously trying to stop piracy, but if other companies follow suit, surely there will be technical solution found sooner or later. Maybe they're just trying to do as much as they can.

Perhaps they don't know that those of us who download and strip DRM aren't necessarily pirates - just looking after own own (legally purchased) books in a system that we prefer?