out of curiosity, have you played MMO's on a PC before? You can very easily still fight while quickly typing here and there. Using the wasd keys to run and the hotkeys to fight, it can definitely be done without too much difficulty. This allows for immediate strategy changes in battle and other important details.
I don't see how someone would be able to keep playing on a controller and type with the other hand. This means that in order to type you have to literally STOP PLAYING for the amount of time it takes you. This completely changes the dynamic of when it is acceptable and advantageous to type a message, thus changing the way the game is played. On a console if you are in the middle of battle and you stop to quickly type something to your teammates or fellow alliance members, you will likely lose very quickly. Not having the option to communicate in that way in the heat of battle prevents strategic conversations or calls for assistance.
Even outside of battle, the console will make communication much more tedious. When in a major city, say someone is crafting or running errands. On PC you can easily keep up a chat while doing these activities. On console you have to basically choose one or the other at any given moment. I believe this will lead to less people communicating because they will see it as a distraction and potential waste of time from what they are doing. That doesn't bode well for creating a thriving and interactive community.