IF Unlimited was tied just to a device and if they kicked you off the moment you tethered... and IF they charged what would be a "reasonable" amount for it (rather than the $30 everyone expects) then fine.
The trouble if they unthrottled it would be that every person on here with the "because I can" attitude would set up a hotpsot, ditch their home internet, and go nuts.
The original unlimited plan was never designed for 3G even! It was setup for EDGE. If you want all you can eat on EDGE (2G), I'm sure they'd be happy to oblige for $30 a month...
Keep in mind you'd be getting .25Mb(b!)ps... and would probably go batpoop crazy with whining, but that was the original plan.
Because AT&T is actually pretty cool about old plans, they kept it for 3G, but started to see an opportunity to make more $$$. If you blame them for that, go to Russia, as they never promised it'd be "Unlimited FOREVER".
They still let people keep it, but in an attempt to make more money, they THROTTLE in the hopes people would abandon the plan. It's still usable, still faster than EDGE (about .5Mbps), and they even kept the costs the same...
If you wanted an unlimited LTE package today, unthrottled, and were going to pay a REASONABLE market rate based on data charges for TODAY, it would probably be $149 per line.
So stop whining about the throttling. I AGREE it's not about network congestion, it's about AT&T wanting to make more money off the data hogs. They let you keep a plan they didn't have to, and they throttle because if they didn't, it would be literally flushing $$$ down the toilet for them.
AT&T, like Apple, is a business. They want your $$$. If you are ALSO happy, so be it, but primarily, they want your $$$.
Unlimited (unthrottled), is a dying breed, and one day all the carriers will eliminate the grandfathered plans too (kicking and screaming to follow). That's why when an opportunity like this came along, I jumped. 40GB should be plenty.