there may be a difference to you, but some men think hairy chests make them manly. it sounds dumb, but it is true. shaving their chest might make them feel less manly (look at some of the responses in this thread for proof of that) do you want to make your guy feel like less of a man? and you can argue that if he really cares for you, he should make an effort, but he can argue right back that if you really cared about him, you'd accept him as he is and not try to change him or his appearance.
if you're not attracted to chest hair, that's fine. what bothers me is the idea that chest hair could be such a turn off that it would make you (not you specifically carmi, i mean in general) not be attracted to an otherwise great person. that's like a guy only dating big breasted women, sure its his preference, but that doesn't make it any less shallow.