I agree with Veg; but on another note, the current system worked great - use Clan Chat only for Clan related topics (this can be hard to achieve with everybody being able to talk.
I'm not sure why you changed that, but if it's only for avatar purposes, that's why we got ranks! I still think that every rank in FC/CC (atleast silver star and above; if not bronze too) should have private chat enabled (atleast if there is lack of other (higher) ranks in Fc/CC; just because we're here to get help to whoever needs it.
But it's true, although we're open comunity, Clan (chat) itself can bring lots of benefits when Nesters want to socialise with others.
Maybe give additional ranks to Clan Chat, to those who're in Clan long enough or have earned certain amount of Clan-XPs (have to be in Clan atleast one week so you can use Citadel and Avatar boosts too) and they are able to talk, but this adds additional work to higher ranked players (in FC/CC) to run everything.