There are some security advantages in using multiple NICs but we fully support onenic, twonic and threenic options so no issue there for support in a production environment.
The only issue with multiple NICs is when a deployment uses that to bypass the inner firewall. e.g. have the Internet facing NIC in the DMZ and the backend NIC in the corporate network so that traffic going through Access Point bypasses the firewall. In that scenario, I too would argue that it is less secure. The security improvement of multiple NICs is acheived when deployed as shown in DMZ Design for VMware Access Point and the use of Multiple NICs where in all three cases, the inner firewall is still required.
Anyway, glad you're up and running and this is answered.
