It wouldn't be pointless for me. I quite often use my iPhone to provide an Internet connection for my MacBook Pro. I wish it were more reliable and didn't consume so much battery. Dell and other laptop vendors have been embedding cellular modems in laptops for a long time. Apple manages to put one in a watch and every other device.

It appears that the Qualcomm license problems are the only impediment to Apple putting an LTE modem into a bigger device.

They pretty much only exist in business laptops because in that context it can be useful to issue someone a field laptop with a SIM in it, and it doesn't really mean much for cost on a large corporate data plan.

What if you want to save battery life on your phone while you're on the go? I imagine having LTE modem in the machine must be a less laggy experience as well.

All of my other devices have LTE modems.

That mobile carriers have not caught up with a better pricing model is not as important to me as having fewer failure points when traveling.

To be fair in some countries providers give data SIM pretty much for free. Here where I am, my provider gives one SIM with data plan for free every other normal SIM, so in my mini company I have 2 company phone numbers and I got SIM card with data plan for free and there was literally no way to opt out of that SIM without paying more.