There has been a change in the system such that explicit write access can only be assigned by moderators. Additionally, there is talk of making it such that sub-20 reputation users will only get a maximum of 4 hours of talk time. Suffice to say - you will be needing your friends to participate in the site in order to enjoy our chat.
I think the third point isn't too much of a problem. Chat isn't all meant to be matters of the site, as a certain philosopher's room on Meta establishes. Sometimes you want just a place you can chat with people you know. To me, Chat has always been more about just being able to chat with the community, not necessarily about it.
I think that it would really help matters if they actually start using the site. Having an account for the sole purpose of accessing one room is... kinda droll. And maybe they might get curious about what goes on in other rooms, or what the site is like. Try introducing the website to see who is interested in participating in the community. 20 reputation isn't a lot, and it opens a whole lot more than just relieving you of the duty of explicit write access assignment.
I'd say go for it if Ivo hadn't beaten me to the punch, though I am curious as to how it would necessarily get any more life here than in IRC considering, among other things, they need to register to use this.
Regarding chat space: This is dependent on whether you feel that it has any use to be advertised. Will you entertain the company of others who come in? Is there room for recruitment of the interested? If neither of those is true, then it would be a problem indeed. While dissociating it from the site is a countermeasure for now, this sounds like something that might be a useful feature for chat in general: some setting which blocks it from the site advertisement (as should be a gaming room) but doesn't hide it in any other fashion. I think this kind of setting would also be useful for those 1v1 rooms people can generate.