I personally think downvotes are unnecessary, because if there's any constructive disagreements to be discussed, it's better to get people talking rather than downvoting. Not upvoting is basically the new downvote, which would make sense if someone is flaming or trying to sow discord, they are basically ignored. Negative attention is still attention, and those types don't deserve any.

Edit: To clarify, I think downvotes aren't a good idea for blahaj but, as others ITT said, will put us at a disadvantage if other instances have downvotes enabled.