Great, then why do you need to tether at all when everything you need to do can be done on your phone? Seems to me that you are making the case that tethering is antiquated, not that it shouldn't be paid for.
Unless that really isn't the case. Unless, as I suspect, you would much prefer to consume data on your laptop, desktop or tablet rather than on your phone. Unless there are some factors that just limit your usage on the phone... after all, when you are on a phone call, it's much easier to surf the web on your laptop than your phone. You may also prefer seeing full size web pages on your laptop or desktop or even a tablet. You may prefer to view Netflix on a larger screen than a phone. That you *can* use as much data on a phone as on a computer doesn't mean that you *do.* If you did, you would have no need for tethering, and thus this would be a moot question.
That's your opinion, and it's a fine one. You do, however, sign a contract. If you don't like the terms of it, find a different service. I hope THAT isn't a relic from some bygone era - the concept of having to abide by, or change, contracts we willingly sign.