I agree a complete change is better than hack code, but is now the right moment to do that?
IMHO now we need to stabilize the version and not change a lot the code, if the adding of the arc tool need change the fields to float, this can affect a lot of places (including annotations), so maybe it's better wait for 2.81 to have time to run a full test and fixing any bug.
I see that you have created a internal function to make the float conversion, so this is ok as solution for primitives. I think in Blender 2.81 we must back here and redo the primitives including a full support for Bezier curves.
It's up to you guys to decide if you want to have a workaround.
Personally if I was working on this, I would just update the code to use floats. It may be tedious but not that risky if you carefully look at compiler warnings, and we're still easily 4 months away from a final release.