If no one spend bitcoin, it will gives bad impact to bitcoin. Without good circulation, the hoarder will influence bitcoin price easier. I think the important thing is not just circulation but spreading is important too.
Yes spreading or letting others know that there is a bitcoin existing that help them financially and everything with their transactions. And you said the possible thing that can happen for real. Just think about these days that those individuals or groups that are holding a lot of bitcoins has making big impact to the price of bitcoin, they are going to have more power when no one is spending it.
Spending the bitcoin and the retailers can keep the bitcoin for some time, that will ease the pressure to sell in exchanges.