Your concerns are valid. Due the MPLS technology is not enabled for workstation, only for access/edge.
However, the operator will have a lot of benefit in the reduction of bandwidth, and they could justify onecanaig a MPLS Ntework with another application fifferente from VPN, and LEgacy over MPLS.
For a While, we will not have VoMPLS at the en user, it is not the goal of VoMPLS.
But, the future could bring everything.