We all want committed people around us, because that motivates us. Committed scope is something that can decrease our motivation and I hope that using the word commitment for scope is something that we could move away from. Instead use words like expected for the scope that is planned for and that a stakeholder can expect to get and uncertain for scope connected to a risk.
All in all there is a lot of value in doing story point estimation with planning poker with the entire team. Done right it will give us increased understanding of what the story is all about, velocity from previous sprints to use when establishing capacity for coming sprints as well as less focus on time and how to keep everyone busy.