Another is that there tend to be fewer conversations at a round table for 6 or 8 or more. Often only one, or maybe two, and that leaves less space for the more quiet people to get in on the interaction. That plus people talking loud to be heard by everyone at the table isn't so cool. Love Sherri's suggestions about noise taming. Here's one more.
Some cooks think it's cool to accompany dinners with music.
Unfortunately no one usually is listening to the music at dinner time, so all it does is make people raise their voices. But while the main consumption is taking place, I strongly prefer no music.