The old open-source question. Why do people work on different projects trying to achieve the same goals each of his own.

There are many reasons for that I think. First of all, everyone has his own ideas of how the ideal gnutella servant. Some want it highly customizable and powerful, others want it simple and fast (or for instance without gui at all) . The second reason can be you don't like the way some developers work (or you don't like the developers themselves). Or maybe you don't like the programming language it was written in. There are a lot of people out there who believe Java is bloated, slow and ugly and they prefer C or VB.

Personally, I believe that much diversity is good for innovation. There are different approaches to solve the same problems, and some developers might think of solutions others wouldn't.

And last but not least. The users have a greater freedom to choose between the servants and can find the one that fits their needs best.