The main reason this happens is because in the code they are designed with a large angle to "seek" an appropriate place for the interactions. Couple that with the fact that if your sim has not yet greeted the other sim, they'll first stand up to greet them. The mod "Less Musical Chairs" addresses this to an extent, but it still happens and it is very annoying. Instead of buffing sims to sit next to your sim, it buffs your sim to stand up and go to the target sim. This is disruptive.
A simple blacklist written for it that bans the need to stand up to interact while sitting down and eating/drinking would go a long way to making this much more tolerable.
