Sorry for the curt reply, I'm about to fall asleep.
In OP's case, I think they're unlikely to see any benefits to using JWT.
Dealing with authN/authZ can grow fairly complicated depending on the business' requirements. On the surface what you're suggesting seems like it would work perfectly fine for many use-cases, so you're not wrong.
JWT is often immaterial to authentication. One must consider how the service is consumed and through which mediums. Depending on the data's importance, you'll need to carefully consider the security model.
Acquiring someone's cookie or token doesn't always mean full access, nor does it mean you get to repeatedly request new tokens. You could require an additional password check before allowing the user to take certain actions. Two examples of this are GitHub and Google.
Absolutely -- In the end to even invalidate a JWT properly you have to either depend on time (so short-lived tokens + refresh token), or store some sort of blacklist (and then you're back to where you started anyway). The world is probably ready for a microservice that does this that everyone can use -- I saw one on HN a while ago but haven't seen it since.
The big benefit I saw from JWTs was the stateless nature, with the drawback of servers using the same key.
In OP's case, I think they're unlikely to see any benefits to using JWT.
Dealing with authN/authZ can grow fairly complicated depending on the business' requirements. On the surface what you're suggesting seems like it would work perfectly fine for many use-cases, so you're not wrong.
JWT is often immaterial to authentication. One must consider how the service is consumed and through which mediums. Depending on the data's importance, you'll need to carefully consider the security model.
Acquiring someone's cookie or token doesn't always mean full access, nor does it mean you get to repeatedly request new tokens. You could require an additional password check before allowing the user to take certain actions. Two examples of this are GitHub and Google.