Experience for prone targets with melee

[Robesidian]

I noticed that when someone with a ranged weapon shoots at a prone target they gain experience but when someone uses melee they do not gain experience. Was wondering why that is? I like to have my Melee characters stay back in a fight while my range characters knock them down then have my melee go in and clean up plus the range characters don't target prone characters so i don't have to worry about cross fire as much. Would like my melee characters to have the same benefits as  someone ranged especially since they have more to risk.