I do think that it serves a purpose. This board can self-moderate, to an extent. If people aren't abusing that, reputation (particularly bad repuation) works well.
As for the good rep, it does make things a little faster for replying to someone. I'm just not fond of the fast reply, you know? By replying directly to your post, Pacha, I'm letting you know I found what you wrote interesting enough to respond. The difference is that other people will also see what we are discussing, and could jump in and agree (or disagree!) and embiggen the conversation.
They've put "embiggen" in the dictionary now, yes?