Some reasons why:
- less netsplits. Even when the main server is behaving well, IRC still netsplits. This is especially annoying for those of us who have access to #tmw-private, since netsplits usually mean getting banned from the channel until reauth, then removing the ban and rejoining.
- less maintenance burden. When I encountered a problem with the services, and asked for help, they were shocked by the version we were using.
- encourage participation. This is not an abstract problem - there are people who won't bother to help with this project because it requires connecting to another IRC server. Freenode is the canonical network for open-source projects.
- recover our old channels
- register new channels, like #tmwa
- change documentation