[srdev]

Since the only frustration seems to be a lack of immediate and instant access to the engineers, I'd imagine that the fix here would be for the product management team to adjust their expectations and communicate better.

Many managers consider frequent communication as being good communication, but more often than not its actually very bad. It is a signal that people are not thinking through what they are trying to communicate. Some trivial barriers, such as a door or forcing people to walk over, are often a good thing, because they force people to evaluate what they are communicating and whether it is worth the effort.