I can't reply to eitland for some reason, but yes, I get both those boxes.

I open the app, click my destination, and then click "Directions". The very next thing is both of those boxes, with "current location" defaulting to the start location. I can then change that if I want.

It optimizes for my most common use case, but allows me to do it otherwise, too. I don't think I could design this better.