There is a hidden thirst need and also a need for washing hands, I believe. It was added for its realism, I guess?
It does bother me when a Sim's multi-tasking includes chatting. It does make things take forever, and I usually cancel it. The two main activities that I can really gripe about is when my Sim tries to do their Conservation tasks in Mua Pel'am and when they are doing university homework - those activities seem to turn my Sim into a social magnet for some reason. I haven't noticed that cancelling chit-chat cancels out everything else though. Chit-chatting in and of itself is okay with me, since I don't want my Sims to be anti-social robots. It's just that they have a lousy ability to prioritize overall.
A thing that really annoys me, on the other hand, is when my Sim can't distinguish between who I want them to talk to and drags all kinds of nobodies into their conversation. That, or the nobodies forces themselves onto my already conversing Sim(s). For instance, if my couple is having a nice time flirting, and a townie decides to make themselves a part of that.
