Just look at games like WOW, Rift, LOTRO etc. Towns that are popular are filled with retards jumping about on their oh-so-kewl mounts like demented 5-year-olds on beany-bags.
I played WoW for a couple years and I honestly never saw this. There was the occasional silly person, but it was far from a regular occurance. I'm really sick of people using "oh, people will bounce up and down and ruin my immersion!" as an argument against jumping. Anyway, Jumping is in, that's the final word. The issue in this threads is what to do with it, not whether or not jump should be implemented. That train has left the station and it's not coming back.