The bottom line is that unless Romo wants to be traded, you do not just auction him off to the highest bidder. You do not treat the face of the franchise like that after everything he has done for this team.
Add to it that fact that he has never been given a good defense to play with, his offensive line was never upgraded until just these last couple of seasons, and he was given a head-coach-in-training that has made many game day blunders that cost the team a chance at victory. Jerry Jones even said that he didn't want to get rid of Garrett because another team would benefit from Garrett learning from all of his mistakes and that the Cowboys are the ones that should benefit down the road from all of his mistakes.
This is not some JAG we are talking about, not some mercenary free agent that didn't work out, not some high draft pick that has not lived up to expectations, we are talking about the face of the franchise over the last decade. You do not just toss him out with the trash.