"Position and hold" is a useful clearance that benefits the expeditious flow of departing aircraft. The safety problems related to this clearance usually have something to do with a controller forgetting that there is an aircraft on the runway after having cleared another aircraft to land on that same runway. However, the same problem seems likely when aircraft are cleared to cross or take off from that runway even if no P&H clearance was ever issued. A recent incident of this second variety occured at LAX.
It seems to me that the problem would be more effectively addressed by witholding landing clearance to arriving aircraft until safe runway separation standards are assured than by eliminating "position and hold", which would address only one of the problems. Concentrating the safety effort on assuring a clear runway prior to issuance of landing clearance would probably provide a greater safety benefit without the negative effects upon traffic flow that will be associated with the elimination of P&H clearances.
All FAA towers were recently required to draft and submit their reasons why these clearances should be retained at their airports or else the clearance would be banned. Nearly all towers did so. Now we see this subject come up again. Without wanting to sound too much like a conspiracy theorist, I must say that it looks very much as though the highest levels of US government want ATC to be perceived by the public as a failed organization so that they can get on with privatizing it. It worked once with flight service. The reduction in runway capacity which would result from elimination of P&H would facilitate this perception. Dovetails nicely with the NATCA contract issues currently being fought over. I wouldn't be very shocked if it came to light that some "supporters" and "friends" of the current administration were ready to step in and "clean up" ATC for a profit. Cronies compensated. Rant over.
I hope this is all wrong.
Best regards,
Westhawk