Might be a hard sell if the company is happy with what they're doing now.

The advantages of a MPLS VPN vs. Internet VPNs are often easier any-to-any routing and some kind of QoS support.

Internationally, might be very difficult to easily connect locally to one MPLS provider. Similar bandwidth, what's available with an Internet connection, might also be considerably more costly using MPLS.

The key factor for pushing MPLS is the capability to differentiate service levels, really necessary for real-time applications, but also beneficial for mission critical or even interactive applications. With Internet VPN, all traffic is just best effort.

Another point, the two technologies are not exclusive.