It is a good idea... the problem is the amount of degrees the rotation would change by in increments.

why yes... a rotatable brush!!!
how brilliant!!!

There is a glitch.
It doesn't always work, but i can sometimes do it

If you hold shift and increase/decrease the brush size quickly, you will find that for a quick moment, it turns upside down
Right after, you can go back and sometimes you can find it

One problem with it though is that it won't work by just clicking, you have to move the brush as you hold the left mouse button and, it is only and outline, it doesn't fill it in

PS. it won't work if you decrease or increase the size from the upside down brush

I tried this with the 74.0 beta version, not sure if it will work with anything else

Just advice

I am NOT positive it works with other versions or everytime