Perhaps the Pro drivers make the same decision many SCCA racers make everytime they go testing and are not required to wear them.
While a great idea .......... the liklihood of crashing and ending upside down seems greater when wearing arm restraints. Reduced mobility and the liklihood of straps ending up wrapped around gear selecters and seatbelt latches are legitimate concerns in modern formula car cockpits. We are not racing the sprint cars that these safety devices were designed for.
I would encourage all to try and wear them .... but they terrify me.
Pet peeve .... It would be nice if 5 grid marshals did not each need to check that we are wearing them .... followed by the 3 grid marshals that each check that our helmets are secure .... followed by ....