As long as there are multiple sources where you can download your paid-for ebook, this decision by B&N will accomplish nothing, other than killing potential sales to people like us.
I don't mind paying $10 for an ebook. I just want a good user experience. This means no DRM and full control of the content.
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?