Well, that's kind of a minor feature and it's understandable that they might decide not to prioritize it. But there are many serious bugs out there that are being ignored.
It would also be trivial for them to ad, as several third-party builds support it and a couple patches have been offered over the years. It's almost certain there's a business/policy reason they don't want to support it.
Sharing a PC's wired connection via ad-hoc WiFi is still a pretty common use case. Mesh networking for communication in emergencies would be an awesome use case, but it depends on a lot of people using it for most of its benefit, and the installation procedure starts with "first, root your phone".
http://developer.android.com/guide/topics/connectivity/wifip...