If I could turn back the clock, I'd make it so that retired numbers were never a thing. Tom Seaver, David Wright, Mike Piazza, Gil Hodges, etc. would be represented on those big circles with their faces instead of their numbers. At least, future generations wouldn't point to a number 36 and say, "Who was that guy?" Instead, they'd point to a picture of Jerry Koosman and say, "Who was that guy?" I think having your face up there is a better honor than having your number up there, and it doesn't deplete the inventory of available uniform numbers.
I guess one potential problem would be if the Mets acquired a guy who looks like Gary Carter. Then fans would be outraged that Gary's face was being reused and they'd force the new player to have plastic surgery.