It doesn't really matter what people think they should have done. As the CBA existed in 2012 they were never going to be a repeat luxury tax offender, period. And it's not like they would be going a little over the tax, the rest of that roster costs some money too, so the payroll costs would have ballooned quickly.
Yes they screwed over a much larger market to move the team to a market smaller than Providence. No, the ownership group isn't the NBA version of of George Steinbrenner, willing to spend whatever it takes. And that's the point, their market dictated that the team couldn't run $90 million + payrolls indefinitely, so they had to choose. If they made a mistake with Harden it was waiting too long to trade him, they'd've got more had they had him on the market that draft night, because every team outside New Orleans would have been willing to put together a package for Harden starting with their pick. By waiting until October they got a lot less.