The data rate over USB2 after accounting for overheads is a lot faster than 100Mbit, so it’s not entirely pointless - you would be able to serve cache files faster for instance. But as soon as you have anything else hitting that bus, your real world bandwidth is going to be < 100MBit.
Since 1G is more power hungry than 100MBit interfaces as well IIRC you can understand why the Pi people decided to stick with 100MBit.
Since 1G is more power hungry than 100MBit interfaces as well IIRC you can understand why the Pi people decided to stick with 100MBit.