Ohh … i really hope there will be a “spam” limit (which you maybe didn’t mentioned because it’s too obviously) of a few messages in a given time.
I agree with you that it’s not rational to add this feature at the current stage of development or before 1.0 at all.
But i like to mention - as i did earlier - that communication (fast, flexible, everywhere) is a key aspect of multiplayer-games for me. That’s something i really enjoy in CS:GO. You don’t need to invite your party (which will be random “match-making” players in most cases) to your teamspeak (which would require time and is unhandy for a short-time-party). If there is something important to say, you just say in the team voice-chat without any delay. That’s a really flexible and handy to use system.
I know that there are a lot of free systems out there. I’m using Teamspeak for years now but there is no common consensus which of them is the best. Some of my friends use Skype while others use mumble and so on… if i need to invite other players to my server or need to convince them why my system is better than theirs i’ll never start to enjoy all the benefits (easy/fast information flow) of voice-chats.