If that's the reason why this specific driver was pulled, ok.
But it shows that there is no technical reason to exclude Ethernet drivers. The fact that the driver does work (albeit with a few bugs maybe) is proof that there is nothing in Windows RT or the ARM architecture or whatever to prevent Ethernet.
So Microsoft not making the Ethernet driver from W8 available to RT is yet another arbitrarily restriction for no good reason (if MS doesn't want to "waste" the few MB, they could put it on the download center).
But yeah, I admit, my theory why they are doing this was a bit over the top. After the mad abilities of Xbone's Kinect (for advertisers), Sinofsky's cynical and manipulative handling of questions on the building 8 blog, Microsoft trying to sell Office 2013 licensing as improvement for the users, Microsoft killing SBS and proclaiming that "nothing has really changed, lol", claiming everywhere that "the start button" will come back in 8.1, while fully knowing that just the sprite in the corner alone is not what people complained about, and the other myriad examples of deceit of the past 18 months, I just expect more in that vein from Microsoft. But the truth in this case seems to be far simpler: It's just yet another way to push the far more expensive Surface Pro units.
After all, if no one needed Ethernet, MS wouldn't have produced this:
So all the suckers who bought Surface RT and thought they could use the advertised USB port to full extend (Microsoft doesn't say that the USB abilities are gimped!) got shafted for buying cheap. Not a bad lesson though.