For one, it’s unethical. But even if you don’t care about that, you run the risk, of looking like a newb, as somebody who does not write a lot of recommendations. Secondly, you run the risk making your LOR's sound similar to each other. Thirdly, you run the risk of the LOR’s sounding very similar to your essays.
THE IDEAL LETTERS OF RECOMMENDATION SCENARIO
What MBA applicants should be doing right now (earlier on in the application process) and without letting the cat out of the bag, approach your boss. Only do this if you think your boss is going to be receptive to you applying to business school. Gage to see how supportive they are and if they would provide you an LOR.