Because there hasn't even been a "decent" offer.
Just moves that put the Celtics into the "treading water" area.
I think the idea is that Danny would be acquiring assets to eventually trade for something bigger. We have that 'something' bigger in KG/Pierce, but they are at the end of the line.
It comes down to wanting cap space [which wouldn't be that much since we are well over the cap now] or a bunch of young players / picks that are either part of the future or can be swapped out for something else.
Danny has never been afraid to make moves. He was horrible when he started [Raef, Wally, etc], but he has won his last few trades and I have no doubt he will continue to do what's best for the organization.