How often is tanking really a problem? I bet nobody can name more than a handful of obvious tank jobs since the lottery began. This draft is supposedly historically great. Every draft is not created equal. You won't see multiple teams tanking for Kenyon Martin or Andrea Bargnani or Kwame Brown.
I guess it depends on your definition of tank.
In my view, you don't have to look any further than this off-season to see teams like the Jazz happily let major free agents walk and use that cap space to take on deadweight salary just for the sake of getting a 1st round pick in the future, or the Sixers trading an All-Star point guard for an injured rookie big man and a probable lottery pick next season, or, for Heaven's sake, the Celtics trading Pierce and Garnett for a bunch of garbage and some probable mid to late 1st round picks over the next few years.
The problem isn't blatant tanking so much as it's the fact that for teams that are just pretty good but not great, the smartest move based on the incentives that the current system creates is to try to get worse in the short term in order to accrue prospects in the future. So you see a lot of teams intentionally moving backwards.
The thing is though Pho, talent in the NBA is a zero-sum game: every player discarded by the teams you're talking about was acquired by another.
So if your concern is the overall quality of play in the league, in some sense it can't be affected by what you're talking about.
In fact, if bad teams are trying to get worse and selling talent at a discount to better teams, this will actually improve the quality of play when it really counts - in the playoffs. For example, the Nets are now another serious threat in the East because of the Celtics' "tanking." The East is going to be a lot more interesting to watch this year, right?
Now maybe you want parity - fine. Even there, however, did Jefferson and Milsap leaving the Jazz reduce parity or increase it? Both of those guys went to worse teams, and now Kanter and Favors will get the minutes they were starved of playing behind those two. I'd argue that the Jazz, the Bobcats and the Hawks will together have a higher quality of play than without those moves. And aren't the Pelicans going to be much better with Holiday - maybe a playoff contender?
Now, if you're talking about coaches or players intentionally playing worse, that's a different story. But the player movement you're talking about doesn't necessarily have to be a bad thing.
PS I actually don't think that the Jazz moves were about "tanking," but that's another discussion.