I absolutely agree with you that EXR image sequences is the way to go for final renders.
The main reason I want to use ProRes is mostly for my pre-vis work. Quick renders that I can slot directly into my NLE and use to edit. I used to do viewport renders with shading, but now Eevee makes a fantastic pre-vis tool. Fairly realistic renders in a fast time. Is it that much work to convert my image sequences to prores? No, but it takes some time, and when you’re rendering out sequences a lot, that time adds up in a hurry, as it just adds an extra conversion program/step.