The chat system was built to be a separate entity and an extremely opt in option. The developers also spent a considerable amount of time developing, testing, breaking, re-testing, breaking, disabling, re-enabling and finally getting it right. Right for SE that is.
Unlike other websites, SE learned quickly that user options are complicated and painful to implement, and 90% of the time not worth the trade off. If an option can't work for everyone, then it shouldn't be there. Giving a user a list of options to complete before they can functionality use it is not worth the tradeoff.
Lastly, SE is not a social network. It's not a chat site. It's a Q&A system. Let's keep it that way. Those that want to be involved in chat, well, they can click on the link and spend their days there.
Disclaimer: Personally I despise any type of online chatting system. Facebook chat and Google chat is two applications I dislike with a passion, and would rather reinstall MSN messenger before using them.
Seriously people, stop trying to turn SE into another social network. Hell stop comparing it to any other website, it's unique, with a unique goal. The solid believe in doing stuff the SE way is why it is such a bloody successful platform