When you think of club finances the way the clubs themselves do - in terms of wages + amortization of transfer fees - this all makes perfectly clear sense.
A potential acquisition as a certain value to the club, X. In a transfer, some of that value goes back to the selling club as a transfer fee Y, and the remainder gets paid to the player in wages Z. X minus Y = Z.
But where Y is zero, the player collects the full value of what he's worth to the buying club. That's not a little bit more, it's a LOT more.
Aaron Ramsey has woken up the football business to this. A player of Ramsey's quality signing a four-year deal worth 200k a week with his club getting a 45M transfer fee is run of the mill business, but Ramsey getting 400k per week on a free and becoming one of the highest paid players in the world seems extraordinary, even though from Juventus' perspective it's the same deal.
(Not *exactly* the same of course, because wages like that for a player like Ramsey are un-transferrable. You obviously want these deals to be a shorter term for a player who's proven and who you know you want. One imagines Juve has figured out a sensible way to insure the contract based on Ramsey's fitness history too.)
To be frank, this threatens to blow up the entire system. Players are heavily incentivized to refuse any moves and to complete their contracts and become free agents, and that's not the way any of this has operated previously. It will be interesting to see how this evolves. Don't be surprised to see Eriksen sign for wages that seem insane in light of the transfer disinterest he's inspired.
20-30 years the club decided for their player. He called him and said, "We sold you to that club, pack your bags". Today the player is more protected and even creates problems at the club. As you say there is an imbalance in favor of the player because maybe the contract is very expensive (if he is tall, like Khedira, it is not easy to sell if the player does not cut the fee).
I think we will arrive at a time when salaries will also go down, like a mathematical graph (sinusoid).