If everyone has their own office, then someone coming into your office is an everyday affair. They could be talking about a programming problem, lunch, or something personal. You don't know, but you would go crazy wondering about it, because it happens all day.
In an open room where half a dozen or so people sit, if two people stand up, walk into a conference room, and shut the door, that's weird and curious.
I work in an open office and grabbing a room with somebody is totally normal—it happens every day, for all sorts of boring reasons. We even have small rooms perfect for this purpose: three or four chairs and no tables or video conferencing equipment. People use them for anything from random conversations (technical or not), personal phone calls or even just a bit of extra privacy and quiet for solo work.
Personally, I've been very happy with the environment. It helps that the open part of the office is bright, quiet and pretty sparsely populate.
> In an open room where half a dozen or so people sit, if two people stand up, walk into a conference room, and shut the door, that's weird and curious.
This also happens all the time, thus not weird. (or people don't talk ...)
> If everyone has their own office, then someone coming into your office is an everyday affair.
Why don't you introduce the rule that entering another office is only allowed for scheduled appointments and emergency cases (life is in danger or the production server crashed).
In an open room where half a dozen or so people sit, if two people stand up, walk into a conference room, and shut the door, that's weird and curious.