For some time now we have had roundness control on shapes within Illustrator and Photoshop, and that hasn't necessarily disseminated properly down to AFX.
When drawing a square mask with round corners, you get one shot when you create the mask, and then that control is gone. If you created a square mask, there's no way to then create rounded corners. Why not instead of having two square mask options, having a rounding control like Illustrator to be able to round all corners, and be able to lock those controls for each corner together, or be able to adjust them independently?
If this could also be added to other shapes of masks too - even better!
We have roundness for parametric rectangles in shape layers, so why not masks? Additionally, this is only a simplified roundness that affects all corners. Again, we should be able to disconnect this and have per-corner roundness control on shape layers too.