Negotiation is something you have to do when there is friction involved in discovering the market price of something. The more efficient a market becomes, the less negotiation there is, with the benefit being the time and effort saved for the buyer and seller. This is why you don't negotiate for things like gas, clothes, and milk.

The only reason I can think for someone to like haggling is it lets them think THEY got a good deal, and makes them feel better about themselves. However, it is almost always in the interest, and benefit, of the seller if haggling has to be done (they have more information than you do, unless you're willing to spend a lot of time and effort).