Something about a salary cap just seems un-American.
If you are at an auction, the person who offers the most money wins. Income and wealth are contributing factors; there will always be haves and have-nots. However an organization should have the right to spend its money in pursuit of it's interests.
People refer to the idea of fairness with regard to baseball and I would like to make two points. First, if we defined "fair" as a positive result for greatest number of consumers or "fans", then a first rate New York team, as the countries largest city (by a long-shot) would fit the bill.
Secondly, if fairness instead means competitive balance, this hasn't been destroyed by the system in place. Review successful teams (by world series and playoffs) and you will see many small market teams that have found a way to compete with Goliath.
Additionally, Goliath is helping David purchase his sling (see revenue sharing), and helping to draw an audience as well (who would come out to watch David v. Ezekial).
The greatest beneficiary of a salary cap would be the owners of small market teams. A cap would allow them to continue spending less while acquiring similar talent to the MLB's major teams. The losers in this arrangement would be the players, owners who can afford higher payrolls, and the more numerous fans of larger market teams.
At the heart of the matter is the issue of whether owners should be allowed this form of collusion. Why should a team that generates more revenue be prevented from putting it back into the team? Does the sport of baseball really benefit from the decline of its biggest teams and the leveling of the playing field?
My answer to both questions is a resounding no. Baseball benefits from its marquis teams (Yankees, Red Sox, Mets, Cubs, and Dodgers to name a few) playing at a high level. These teams also generate attendance and revenue in their road games and when participating, help to make the playoffs a more marketable product.
In summation: The current system while imperfect, it isn't broke, and has certainly been entertaining and lucrative.