Like you, I rarely feel the need to tether, but when I need it, I need it. Sometimes I'm in a hotel and their free LAN/wifi access is garbage, or I'm in an airport that wants to hit me for $9 to use the wifi for an hour before my flight. In many of these situations, using my phone will be good enough, but sometimes if I need to type a long-ish email, tethering is very useful. But not $30/month useful! And that's, I think, why Sprint has been hands-off with light tethering -- they know they're not going to get the light user to pay for a mobile broadband plan anyway.

I'd gladly pay $5 for an officially-supported tethering plan with a pretty low bandwidth cap, but such a plan doesn't exist, so I'm gonna go the unofficial route like I always have. If they want to keep me as a customer (the early termination fee is less than the cost difference between Sprint and AT&T service, and Verizon is getting the Pre in six months) they'll let me do it.