We will discuss this. Personally, I think this request makes sense. Basically for the reason that the COPY may take considerable amounts of time with large tables and then the user need to take a coffee-break for as long!
I remember that the CREATE/ALTER TABLE was a modal dialog in old versions (more than ~8 years old, as far as I remember). To avoid the modality we implemented it in a TAB instead. This may be a solution here as well. I will ask developers to check if this is feasible.