I agree, I think this issue receives way more discussion that it warrants it. I think there are more than enough measures in there to prevent true "tanking" and I personally see no reason to change the rules.
I personally like the idea of an exciting trade deadline and I think deals spur fan excitement. If you are going to incentive teams to need to win to the last game I thikn you are going to see less player movement. That trade off isn't worth it for me.
but in all honesty I think the NHL has the balance right and the best rules in terms of handling "tanking" of any of the major sports leagues.