There should be a "Hold Position" option for rotators and hinges. Basically, what it does is that it keeps the position of the rotator and the object it is attached to it, instead of moving back to the original position it was in when letting go of the input. This would allow for way more freedom of customization, be it radars, walking legs, turrets and so much more.

Another great thing would be a "Cycle" option for rotators and hinges, which is basically what the piston does, except for the fact that it rotates left-right instead of extending and retracting, I don't know any ideas for what it could be used for, but there's definitely a use for everything.