There were other issues with the combadge anyway. Take this convo:
*Picard pushes conbadge*
"Picard to LaForge, meet me in transporter room 3"
Immediate response heard through Picard's combadge: "Aye, captain."
Problem is, the com system had no way of knowing who to route the message to until Picard says "LaForge". Since you can't just cut in the audio after the "LaForge" (Geordi would just hear "Meet me in transporter room 3", which would likely get the response "who the fuck is this?"), which means the com system has to rewind and play the whole thing (which is what the show shows anyway). But, now you got a delay in the system, and the response can no longer be immediate.
/nerd