I see that I'm pushed by my subconscious to keep in good consideration fellow monks that have a high level, and therefore a high experience.

Big mistake, Just look at my XP ;-)

if I get many points from many obvious posts, their weight is reduced

I assume you've taken a look at the Voting/experience system. Many posts with low reps will gain you less XP than a few with very high reps.

I soon realize that many many low-level monks vote as many nodes as possible without thinking just because there is a chance to get more xp points

Yep.

This inevitably leads to a distortion of the whole system

Yep.

The voting system does provide people with a small incentive to examine what they're posting a bit closer, helps moderation a bit, and encourages people to vote on nodes to achieve the two prior goals. So it does have a bit of use. It isn't an accurate measure of anything though, so I wouldn't worry too much about it :).