After having spent Three Plus hours trying to get the wifi running, I absolutely agree with this suggestion.
This is not a simple IOT device like a light bulb or a switch. It is a full fledged computer.
Adding ethernet NIC does not add much to the Bill of Materials since it already has a full network stack for the Wifi. It will save a lot of hassle, at least in the initial setup. Probably save more in the support costs, and return of controllers which do not work than the cost added.
I have run an ethernet cable to my garage, added a new Wifi Access Point to the garage and then struggling to get past the yellow flashing light. Have tried connecting directly to the Raico-xxxxx wifi network but no luck from my mac air or iphone.
While Wifi is a necessity, it helps to have a fall back available. Even if it is just to clean up the messed network config files.