Indeed, disabling down vote would force people to write a post.
No it wouldn't.
People would just think 'man, what a moron...' and move on which does nothing to point out the poster in question is, a moron.
Or, I guess they might post they are a moron, at which point bring on the flame wars and moderation dance.
(or you'll end up with lots of down votes with the reason of 'asfada' or similar.)
Most people who down vote WILL say why anyway in an answering post, about the only time this doesn't happen is if someone has down voted, explained why and you agree with that reasoning (at which point you get a down vote/up vote pair) - the down vote IS useful still however as it lets people following know at a glance that the community thinks the information is rubbish or the posters attitude is rubbish.
(Of course where this breaks down is when someone down votes, someone else replies to correct and the poster who was down voted assumes the person replying down voted them and goes on a down vote crusade... but given they were a moron it's hard to stop that.)
Personally I think the down voting has been a good thing; this site is a lot more sane than it use to be and generally it has been a massive improvement as it's funny how (not referring to the OP here) people's attitude change when a number goes down (often accompanied by a rant about how they don't care about a number... *makes chinney motion*)...
I guess if you want less down votes and no more posts then disabling them is a way to go... but... eh.. *shrugs* I'm just opinionating for the sake of it really, I hardly drift by these parts any more...