We have players in different time zones, some of us are something like 12 hours away from the others. That would make a chat room very difficult. Personally, because I have been in rpgs which used chatrooms and that only managed to make the game run away from those who don't have the time/are not in the same time zone, I do think it is really necessary to chat in real time with the players.
What's so bad about waiting a day for an e-mail reply?