The FAQ says this which probably explains the the problems many of us are having.
http://www.limewire.com/index.jsp/faqs#fir1
The Firewall/Router issue about if two peers have the firewall/routers they can download from each other. My guess is that there are many of us out there using a filrewall/router with our broadband/dsl connections. It's just a good idea.

<question>
My QUESTION is:
Why can the people that contribute to the LimeWire code figure out how to deal with this issue?
</question>

Other peer to peer software can. I bought the pro version for my Linux desktop and XP Laptop to support a good cause, opensource, multiplatform, and Java (a nice java app imho) . I fear LimeWire is going to fall to the way side.