Allowing play won't help anything - it will probably actually just make it even worse because the motor will spin unrestricted for that tiny distance and 'hammer' the plastic gear every time the window goes up or down.
Those plastic bushings are not super hard plastic the way metal is. They are actually ever so slightly flexible, which you can tell when you have to press the metal gear into the plastic gear with the bushings in between them. That tiny bit of flex makes for a super tight fit, and lets them provide cushion to the motor and moving parts.
You can even "feel" the difference when installed, the plastic bushings feel like a new motor when you hit the switch, and it goes up and down like you'd expect. Metal nuts or aluminum bushings still make it work, but it's a harsher response when you hit the switch, all because of the lack of that little bit of cushion.
I'm not saying that there isn't a better material for the bushings, there probably is, since Ford has been using those plastic bushings, unchanged, since the 60's. I'm only slightly surprised that an effort hasn't been made to use a tougher, more durable modern material that would provide cushion yet not get brittle and harden with the temps a vehicle is exposed to. Ford and the aftermarket probably make a ton of their money replacing entire window motors when it's just the bushings that have gone bad, so it's unlikely they will improve something that's making them money. Sucks for the customer and the environment, though.