Agree with the first half of this, the people who hate grade bumps are either professors (sorry the undergrads are stealing your precious SDN time, by the way), or hateful hateful premeds. Go ahead and ask for the bump. You don't need to worry about a letter of rec, BTW. You won't be going to someone whose class you didn't get an A in for one of those.
The idea that this stops after Undergrad, though... seriously? If anything what stops after undergrad is the illusion that you're being rewarded for your work, rather than your interpersonal skills. Medicine is better about this than most professions, but still no where as 'merit based' as a undergraduate degree in the sciences.