Most people prefer 0 bounty simply because it's a hassle otherwise. It could be aggrivating to have to get bounty all the time, depending on what you had your server set to as far as giving bounty and how much things would cost. Also, a lot of people like to mess with different clothing and change it up pretty frequently, so making everything free makes it easier on them.
I can't really think of a negative side to it. I guess some people think it is more of a "challenge", but I don't see how trying to get more bounty would add any enjoyment to the game. I personally would have everything up for 0 bounty if I were running a server, not all at the same level of course.
Here is a link to the Zitem Tools program, which is a nifty little program for multiple reasons. You can use this to change the price of everything to 0.
http://forum.ragezone.com/f245/zitem...-1-1-a-510952/