I personally believe that the "serendipitous random hallway conversations" thing is totally overrated. I don't deny that it probably once in a while leads to a great product, but how often? Quantify it! Moreover, if your business depends on this element of randomness to provide value, I'd argue the opposite: you have a process problem that needs to be addressed. Brainstorming and ideation should not be dependent on the roll of dice.