Sometimes it's more efficient to be in that meeting, and half-listening, rather than dealing with the fallout from bad decisions made without your ("wait, WHAT did you say?!") input.
On the other hand, it sucks being a person who is saying something in a meeting and then get interrupted because someone misheard something or didn't understand the context. Or when you ask a question to a person who is attending the meeting but they need you to repeat what you were saying because they weren't paying attention.
