On one hand, you'd assume that a bubble hovering above someone's head would be an obvious immersion breaker, but here I actually think it would help me sink into the world a bit better.

As it stands, one of my few issues with the game is the disconnection between the chat box and the characters; you don't know who's talking, it doesn't feel like anyone is talking.. and most importantly, I don't feel like talking to other players either. I fully support this feature.

Lol it doesnt cause slowdowns. rendering a chatbubble is easy compared to the entire view. Maybe you loose like... 0.5fps if the screen is all chat bubbles.

Regarding clutter, yes that's actually realistic. Have you ever been in a city? Its noisy as all [censored] compared to being in a forest in the middle of nowhere. You are literally bombarded by people talking.

But it will hardly clutter. Why? Because in general, people dont really chat that much. An earlier argument with "I dont want it blocking my screen in PvP!" is just lol. Complete lol. How many people will keep chatting while they are fighting players? Haha, its not a problem in GW2 WvW and it wont be a problem in ESO AvA.

Also it would be incredibly easy for ZOS to add an on/off option in the graphics/UI menu.

Yes there will be a massive clutter cluster [censored] if there are chat bubbles, because people will be using them in massive groups of 50 in the middle of the city, your whole screen will just be fracking chat bubbles. Of course you are bombarded with noise in real life, but real life and in game are two completely different things.