If the problem with the ethernet port is the size of the connector, why not design a smaller connector? It's not live they haven't released miniaturized connectors before (think mini display port). A mini-RJ45 to RJ45 adaptor wouldn't need to do anything clever and could support gigabit ethernet. Or am I missing some technical or political hurdle?
We think alike. Ethernet is a few pins and a lot of bulk--it should take Apple about 20 minutes to make a new miniaturized port for this. Then they can sell two new products: a Ethernet to Mini-Ethernet cable for home and office use, and a teensy little converter for travel. Not a corded dongle, just a little plastic pin adapter that can fit in a backpack pocket.
Throttling Ethernet through USB2 is misguided, I usually hook up to Ethernet for higher speeds and more reliable connection than Wifi. The ugly dongle solves reliability, but not the speed issue.