Baseball Salary Cap

Why is it that so many professional sports have salary caps yet baseball still has none? Does baseball enjoy having some teams be able to spend over 200 million dollars on payroll yet have others spend only 40? I know that the MLB is a players league but I think that it has become a little bit too rediculous.
The New York Yankees are a perfect example. The yankees play in one of the biggest markets in the MLB and therefore have money to throw around. Just this past off-season the Yankee's spent around 100million on free agents such as C.C. Sabathia and Mark Texiera. But if you look at teams like the Tampa Bay Ray's their payroll is less than 50 million a year. Such a drastic difference between the two teams goes to show why a salary cap is necessary.
Since there is no salary cap and because some teams can afford to spend a lot more on talent than other teams, some teams then have an unfair advantage over others. I know that payroll alone doesn't decide who will win, but it doesn't hurt any. But if we look at other leagues like the NFL we can see how the salary cap makes almost every team competitive.
Also, why is it that players in the MLB can get so much more than players in other sports? I personally believe that if any group of players should get the most money it should be the NFL players. They put their body on the line every game and are at risk of injury more so than baseball because of the added contact. So baseball should implement a salary cap. It would help to make the league more competitive and help reduce the insane amount of money that baseball players are getting these days