I know you disagree, but I still think front office resistance to trade demands should be directly proportional (not inversely) to player quality.
But here's one other difference between the Webber situation (or, lest we forget, the Cousins situation with Westphal) and the Dedmon situation. Webber and Cousins were not here by choice. Webber was traded here, Cousins was drafted here. There's a certain extent to which a front office has to put their foot down to protect their CBA-established "rights" to a player they trade for, or a player they draft. If you trade for players *that you want*, or if you draft players, and those players are on your team without their explicit consent, you can't just let them go because they complain. That would establish a precedent and severely hamper the team when trading for/drafting players.
Dedmon, on the other hand, *freely signed* his contract to be here. Unlike Webber and Cousins, he was responsible for his own mistake. Now, we don't anticipate this happening all that often, but when a player signs a contract, and then regrets it (and you feel you aren't going to be getting full value out of that player, due to attitude or whatever) then it's probably best to let them go. It sends the message to future free agents that if they think they want to be in Sac, but then they decide they hate it, they've got a decent chance of being accommodated in a move somewhere else. That would make free agents *more* likely to sign here because they can see there's at least some insurance for regret. If we refuse to move Dedmon when he's unhappy, why does the next MLE-level player sign with us if he's not 100% sure?
TL;DR - Offer "second chances" on FA contracts, particularly mid-level ones, to increase the probability of FAs signing of their own volition. Do not offer "second chances" on draft picks and trades, particularly high-value players, to prevent wastage of draft picks and trade assets.