Simply put, because itís the rules. Prior to the room exception, the only sort of mid-level exception was for capped teams. Teams using cap space went up to the cap limit and could do no more. The theory is that cap space is already more valuable ó you can sign players to higher salaries, you can acquire them with trades, etc. The various MLEs, room included, are less flexible. Since cap space teams have more flexibility as is, capped teams needed some way to acquire a free agent for other than the minimum, and thus the MLE was born. They added the taxpayer version to punish those with incredibly high payrolls, and the room exception to throw a bone to those filling their rosters with max players.