Of course this would be immensely useful. For example, can I put this in my vehicle with built in maps (or just have a hotspot in my vehicle to use with a tablet). As a price comparison, in the us there are some EVs that charge $100/year for basically this, most charge a lot more. That's $8.33/month, so only a bit more than $6 or 7. But in the us it's hard or impossible get anything that low for just raw service, I can't find anything like that.
Yes. I paid 5 €/month for LIDL Connect for 1 GB. I don't need much mobile data and in just a few months the cost of the adapter is amortized. It might also come handy in the future if I travel abroad.
The stated reason is because you can call premium services and run up a charges even with a free service.