PA (and specialized RNs/NPs) are the best bang for buck careers right now. Low opportunity cost, no overheard, short training, minimal personal liability, much better hours, all for a six-figure salary that is actually higher than some MDs (170k for example is more than a good chunk of FP, neuro, peds docs).
I enjoy medicine, but when kids ask me about going into the field, I ask them to make a serious cost-benefit analysis considering all of the above before they chose MD over PA/NP. The system/patients would benefit from more MDs, but it's probably in an individuals best interest to become a mid-level.