conversion? no.
plexi was put on panels so that the cracked and ripped up vinyl didnt bother the players hands. vinyl will eventally peel at the edges, and will crack given time. when this happens... it makes a nice sharp edge that gouges into your skin. then, you rip off the part that is poking you... but eventaully, it gets worse again. you can see this on most old classic cp's.
the plexi prevents lifting, as well as makes it easier to clean... as without it... hand oils and dirt will embed itself deep into the vinyl.
yeah, it will take a while before it happens... but when it does, its a nightmare to remove and redo. plexi's basically a one time thing.