This argument seems valid when the company’s network has no shortage in IPv4 addresses. However, this may change if the number of users in the network increases or new services need to be implemented. Also, other services (from potential business partners) might be reachable only by IPv6. Depending on the specific case, this may or may not be an immediate problem for someone running an IPv4-only network. But at some point the IPv6 usage will reach a critical point and IPv6 connectivity will become a must.