Yeah, it is a curse. How many teams are screwed financially because of a top draft pick being a bust? The rookie salary cap would help alleviate that, but there's no denying that the Lions weren't screwed with their top 10 busts. Yes, it is their fault for tanking the picks and not trading down.
I think a lottery of the bottom five or so teams would be somewhat interesting, even with a rookie limit on salary. Plus, it's another opportunity for the NFL to make money, because obviously they are hurting for cash if you listen to the players union and the owners.
Seriously, I think the concept is neat, but I don't know how to properly incorporate it. Teams will and can still tank a season (e.g. Spurs) to get the overall number one pick, or increase their chances of it.