Rachio's current viewpoint is that Ethernet connections are restrictive. My guess is they have good market research + good economic product research such that they have concluded that for the residential market the cost of adding an Ethernet port in addition to Wifi (or making a separate hardware version that's Ethernet only and taking out the cost of Wifi connectivity) is too prohibitive relative to the incremental revenue to be received.
My guess is for the commercial market indeed it's not a Rachio focus at this time. I can't imagine municipalities accepting WiFi connectivity now even in spite of it's mainstream acceptance now from consumers. Now we're talking recreational parks, athletic fields, visitor reception centers dependent on bookings (and thus their drive up appeal), and golf courses, to start the list.
My initial reaction is of surprise that the commercial market isn't a focus at this time. But, further thought says that perhaps the plate can only be so big, and at the moment Rachio's plate is overflowing just with residential focus. And if so, then I'd agree, stay focused on what they can do well, and expand to commercial focus when company capacity allows.