Is it really true that you can't set your status/presence in it STILL? I only ask because I have been on Google Talk since Vic Gundotra announced the new Hangouts at Google IO 2013 with much fanfare, yet failed to mention that this basic feature was missing.
It's so elementary in an IM application - even MSN Messenger had it!
I don't think it's 'missing', it's more like they opted out of having it.
Hangouts is going towards integration with SMS and is supposed to work the same way (i.e. you send a message to someone regardless of their status).
Whether this is a good thing or not, I don't know. But it sort of makes sense in a way. IM seems to be the only form of online messaging where you decide whether to message/call someone based on their status. If you call someone, you have no idea if they are available or not, same with SMS or email.
I also often see the case where a user will perpetually set himself to 'Away' or 'Busy' as he 'never' wants to be messaged, defeating the whole purpose of a messaging service in the first place.
If this is still missing, it's stupid.