My opinion is yes. You should create a cluster for standalone hosts. I makes life simpler in the future.
My reason to create clusters for standalone host is migration with vMotion. vMotion requires compatible CPU settings – the EVC mode. EVC mode allows you to hide newer CPU options from VMs making it compatible with older CPUs. You usually don’t do vMotions on standalone hosts – but it might happen every few years when you do hardware life cycle upgrades. With EVC mode enabled you can add new host to cluster, migrate VMs from old host to new and remove old host from the cluster. Simple life cycle upgrade without any downtime and hassle.