I have a userscript to actually hide my own karma because I always think it is useless but your point is good actually. But also I think that karma/comment ratio is better than absolute karma. It has its own problems but it is just better. And I would ask if you can share the userscript.

And to bring this back to the original arxiv topic. I think reputation system is going to face problems with some people outside CS lack of enough technical abilities. It also introduce biases in that you would endorse people who you like for other reasons. Actually some of the problems are solved and you would need careful proposal. But the change for publishing scheme needs push from institutions and funding agencies. Authors don't oppose changes but you have a lobby of the parasitic publishing cartel that will oppose these changes.