Language lines in archived threads not revealed?
And playing devil's advocate (actually, I have Class levels in that) ...
Prior to the languages functionality being introduced on RPoL, I used to merrily type in my own pidgeon Dwarvish/Elvish/etc from the various languages dictionaries to be found on the interwebs. Other players of my acquaintance have used other variations/made up languages for flavour when casting magic spells.
I can guarantee that if those threads are archived, you're not going to be able to read those manually typed fantasy languages ... so why should the language functions be treated differently ? Yes, they could be, as the plain text lurks behind the curtain, but that's not to say that they should be.
Either way - if it's deliberate or an oversight, it doesn't matter - usually process applies, if someone wants languages to be revealed in archived threads then they need to put up a request in RPoL Development for other user to vote on and for jase's consideration.
Personally I don't want it, but then again I'm with others here, I don't intend to archive threads anyway, so I'd not vote for or against.