* You can't have a normal conversation with that much delay. Every time you talk you're probably interrupting someone, and that starts to wear on you.
* You can't have any side chats with your neighbors before and after the meeting, making everyone seem less like a person.
* You can't tell who's looking at you, so you always feel like you have to remain presentable and vigilant.
* There's no sense of space. You can't look over at person if whomever is talking just teleports to the center of the screen. Or if the layout is fixed, sound isn't coming from anywhere in particular, so you need to search around for who's talking. And everyone on screen is looking a random direction.