Cellular iPads are amazing. Absolutely worth it if the iPad is your main computer.
I no longer pay for a cellular plan as my main device is a MacBook, so I'm going to be hotspotting regardless. My iPad is only a main device when I travel overseas occasionally, and in that case I have to hotspot because only my phone has roaming data. So there aren't enough scenarios for me where it's worth it anymore. But I do wish my MacBook had cellular.
It's good to have an alternate carrier. My iPhone has a work SIM and a personal SIM, both on a different carrier. Until actually having this dual SIM setup I would have said it is unnecessary, over-preparing etc, but it actually comes in handy way more than I would have thought.