While you can sometimes (but you are right--not always) take the classes for your own benefit, you do not get any Category 1 credit for taking CME classes, which I assume is the type of credit you are looking for. When you register for these classes, the course will ask you what your credentials are, so as to provide you with the appropriate credits (i.e. physicians and nurses can sometimes take the same course but will be awarded separate types of credits--MDs refer to these as CME, nurses call them CEUs) and as a med student, you do not qualify to receive any. Even if you did, there is nowhere for you to log these credits, nor do they count for anything. You can not backlog CMEs. In other words, you can not stock up on CME credits now and log them later once you are done with training. Plus, many of these classes are costly and some may still expect you to pay, even of you aren't receiving any credit. I don't think taking a bunch of CME classes will boost your CV when applying to residency either.
If you have a separate degree or certification (EMT-P, RN, PA, etc.) you are trying to maintain while in medical school, that is a different story. In that case you do need to continue logging CME hours just as if you were still working full time, and be advised that attending medical school does not count toward "continuing medical education."
Just out of curiosity, why do you want to take CME classes now?