I personally agree, but where does everyone come up with this $20 a month to tether price? The Unlimited Mobile Hotspot is $30.00 as an add-on to an unlimited plan. My corporate discount brings it down to $24. I assume those who have tiered data pay $20 and that's where this is coming from?
BTW - Verizon does have the right to charge for tethering on an unlimited plan. While I disagree with it, it's their right from the sounds of it and they can say you violated your unlimited plan and must switch to a tiered. I could be wrong, but they give options even though the options both lack any logical sense for the consumer.
They did away with unlimited MHS a while ago. You're stuck with tiered or shared data at this point. Verizon made the words unlimited and data mutually exclusive.
On your second point, Verizon can't say how to use mobile data more than comcast can. Comcast originally only wanted one device plugged into their service too remember? The problem came when people started plugging in routers. So Verizon beat you to it by giving you a paid for multi-connect.
Lastly consider this. Data access(bandwidth) is a self renewing resource. You use it and once you're done you add back to the pool. It is far from finite. Companies that treat it like it is are obviously out for the cash-in. Don't let them treat you like you're a fool. Treat them like the dumb pipe they are. Leave, and get service that doesn't charge an arm and leg or place artificial restrictions on artificially renewable resources.