I propose that the MAC address, under the "network" tab, should be optional when creating a new host.

I'm using the Foreman (together with CloudForms) to create OpenStack instances. The workflow I'm using is to first create a host profile in Foreman, connected to the appropriate host-groups etc. and then crate the OpenStack instance with a puppet certname matching the host profile.
In this workflow, I don't need Foreman to know the MAC address and using a dummy one is a bit painful since Foreman checks for duplicates. Therefor, making the MAC optional would be beneficial