I really don't think letting people jump is going to hurt the atmosphere of the game. If it is properly implemented, it could only help I think. Having people bunny hop around like retarded kids would suck, but you should be able to jump over small ledges and fall down cliffs(fall damage and death if too high). Having to walk all the way around stuff can get annoying. I know it doesn't seem like such a big issue but all the little things do add up. Maybe they can tie it in with some kind of fatigue system so people are not running around hopping like rabbits.