Standard PoE+ is 30w, and even the newest PoH maxes out at 90w. The new hardware draws more than that, so Starlink made up their own PoEish standard with proprietary cable/connectors. The $20 dongle is probably a custom PoE adapter. The good thing about this setup is you only need a single cable run up to your roof.
Adding an RJ45 jack directly to dishy might actually complicate the construction. For one thing, it's a weatherproofing issue. But now you have two ethernet ports and need a switch, which needs software management. It's not just a few pennies on the BOM.
My understanding for the newer routers is there is now only the single port. The router itself doesn't appear to be weatherproof'ed in any way, and already needs to be installed indoors, so I think it'd just be the cost of the RJ45 jack (and whatever internal differences for the router).
It just...seems like it cannot be much of a cost savings.
Surely whatever SoC they're using already has the capability, so yeah, it's probably a few $ at most. I bet they figured they'd save money because of people's shitty wifi setups in their gargantuan exurban homes.
We're talking about a typical 1 Gbps (non-PoE) LAN port on the router, so you could plug in another computer hardwired (or a switch).
The jack is pennies, and the rest of the chips to support the extra Ethernet interface are still readily available. Version 1 of the router had a LAN port (labeled AUX).
That can’t increase the BOM that much, right?