Harris got overrated once he was given carte blanche offensively but he's still a nice player on a good team and, I believe, fairly compensated.
That said, it's going to be a long time til the Nets are good again and Harris is 26, i.e. young but not young enough to wait through 3 years of nebulous rebuilding.
If they can land a top 10 draft pick for Harris, that might be in their best interest.