Much has been of the very slow free agent market, and the fact that collusion is suspected. There are some other very valid reasons:
1. As has been mentioned, everyone now better understands the true value of players, and they now realize that when you sign a 30 year old to 6 years, you are probably only going to get 3-4 years of the current production. Then maybe nothing.
2. Why would GMs give offers to free agents early if they know there offer will only be used against them, and used as an opening bid with other teams. More and more agents consider the first offer as the absolute floor, no matter how big it is. As owners and agents both get smarter the market will change.
3. I feel(no evidence) that agents discourage players from spending their career with the same team. Molina and Wainright are the exceptions these days, not the norm. Switching teams gets a larger immediate return to the agent, but may hurt the player in the long run. Pujols should never get a beer distributorship or statue in St. Louis. Molina will be enshrined forever if he wants to be.
4. I'll admit that I have trouble feeling sorry for people in their late twenties and early thirties who say $100 million is unfair. I don't resent them making what they can, but please do not expect me to berate owners over refusing bad deals.