Draft picks are overrated in trades, picks in the late teens and 20s are worth half of those from #6-15.
They have value, but not to the extent they're going to turn a franchise around, they're more useful for obtaining solid depth. The solid prospect near to the NHL (thus lower risk), is as good or better.
If you don't blow those high picks with Patricks and Pitkanen's, that's where you get the 3 or 4 players you need for your core, add some complementary players from acquired draft picks and prospects, and hit on a couple picks after the 1st round.
If you just depend on high draft picks, it takes a long time to accumulate enough to make a difference, Edmonton being a good example, and by then you're paying your high picks big salaries.