BF3 is an FPS not a RPG but I'd agree that some grinding teaches you that some things in life come at a cost and aren't just given away like candy (like one of the top Sergeant ranks in BF2).
And dedication like these saddos:
Seriously, check it out. I can't believe one guy must be playing an average of 23 hours a day? Guess he must either be a robot or have a serious multiple personality disorder whereby there's physically actually more than one of him.
I love Samson's idea about reverse weapons unlocks. It'd be so cool to be standing there with just a knife growling "bring it on!". Hardcore or what? Not much use against tanks though.