Probably because they're working on a new forum software?
Anyway, not everyone would use 2FA and even if you enforce everyone to use it, issues like unable to login due to 2FA would become the new problem.
https://bitcointalk.org/index.php?board=167.0it doesn't have to be mandatory. but users who are worried about security would have that option
"issues like unable to login due to 2FA would become the new problem"
are you saying it's better to have hacked account and hackers to scam with those accounts rather than a few users who don't know how to use 2fa to complain?
I don't see why but maybe it was difficult to implement that in the past
and I understand it's not worth putting a lot of effort developing something if the new version of the forum is about to be ready
but $15 or $20 and a few clicks?! it's already done, ready to be easily installed
it's like if someone already completed that bounty but charged $20 instead of 2 btc
it is worth even if it lasts 1 month before the next forum version! and I doubt it will last less than several months or more than 1 year