I like Shane Doan’s idea; The draft lottery odds are assigned to the non-playoff teams based on the order (not reverse order) of the post-trade-deadline W%.
Can't do it that way...there could be a team who's really a top 10 team in the league, but early injuries put them out of the playoffs, but yet they would have received the most points after the post-trade-deadline. Now you've just given a top 10 team the best percentage to make them even better.
For better or worse, the best way to help the bottom tier teams win is the current system, albeit, I'd only let teams move up 5 spots. I know it's arbitrary, but there are generally 4-6 teams that are truly worse than everyone else and they should be given the opportunity to improve the most.