"pretty rude to keep gaining exp like a mad thing because of a small reply node to a small root node."

Don't feel that way. Okay if you still feel that way, let me give you two reasons why you should not ;-)

• First of all, and most importantly, small node is just as important as big node, long node. Whatever it is a reply or an original node. You participated, you helped, that's all it is about.
• It is fair, the same rule has been applied to you, as well as others. You were not treated more kindly ;-) You might get luncky on one day, that just what rand does, another person might get the luck another day.

Hey, it is all about the fact that you helped!