Do steroids matter in baseball? Yes and for the following reasons. Cheating has been part of sports from the days of the Olympics so what Barry Bonds and Jason Giambi have admitted is not new. It was wrong in ancient Greece and it is wrong is now.
Call this another example of the "moral value debate." It is not about sex but about cheating. Steriods are illegal when it comes to using outside the approved labeling and when not supervised by proper medical personnel. It is one thing to enhance your athletic performance by natural means like weight training and hard work outs. It is another thing to put your health at risk to do it with drugs. Not every baseball player uses steriods but many do. Those who don't are put at a disadvantage by those who do.
For the average baseball player, it is not hard to see why. You can earn millions of dollars to play a kid's game and become immortalized heroes in the process. So the temptation to cheat is great when you consider the money involved for both owners and players. The key to this debate is that players are giving themselves advantages over those who don't cheat and that is one of the big issues.
Another reason is that employers do have a right to insist that their employees perform drug free. While many libertarians will insist that no company or organizations have a right to interfere with a employee private life, companies do have a right to ensure that their employees perform at the highest levels. Using drugs do have a negative effect upon many workers efficacy and it does matter to a private corporation if a employer peronal habits effect his or her job. Baseball is no difference. If a juiced up player affect the outcome of a game, it also hurts the intregrity of the game. So baseball has an interest in ensuring that faith of the game is not shaken.