TV stuff doesn't tend to need more than 100Mbps, unless you're playing blu-ray 4k discs which have higher peak rates. Saving a buck or two on the SoC adds up for the manufacturer.
Totally. It's only inconvenient for a total rounding error of a customer who's trying to stream games from cloud or sunshine/moonlight, where it can cost up to 4ms of latency for higher bitrates.
It is so frustrating that this can bring down the rest of the network to the lowest common denominator. I know it is the fault of a cheap switch, not the TV, but still.
Even UHD Blu-Ray isn't likely to need sustained transfer rates over 100 Mbps. The spec allows transfer rates of about 128 Mbps, and some discs reportedly have momentary spikes above that, but I suspect the vast majority of titles would be playable over Fast Ethernet, especially if given a few seconds of buffer.