Medic is definitely rare. Never in past Battlefield games have I constantly been the only medic on my team. Yes medic is good on a map like Underground but go play Panzerstorm, Hamada, Iwo Jima, Al Sundan, or Twisted Steel. Count out how many medics you see out of 64, I bet frequently it is less than 5. Yes medics can do well on these maps but it takes 5x the work of the other classes, barring Scout but the scout SLRs are really good on these maps.
did you even bother reading the post?
its no secret that the medic is the least versatile class, and before you even start again i know you can be so good it seems like you are cheating 
but we mortal men have our limits.
just compare the load-out versatility of the assault with the medic and you will undoubtedly see that there are some staggering differences.