what you must realise about the rotate tool is that you can have the coloured protractor on any surface.
Say you have a complex object and you want to rotate it using the blue rotation.. Place the protractor on any horizontal surface and click - move in either red or green direction, click again then you can rotate the whole object without trying to find a blue rotation point on the object.
I happen to like the rotate tool and I use it all the time as I rarely have a 90 degree corner.
I hope this helps.