might depend on the model, but my parents bought a weber maybe 4 or 5 years ago, still had stamped metal tables. For the price weber charges, it should be.
Im not sure Id choose plastic, whoever does use it, likely uses a high temp type, as the table adjacent to the chamber can get quite hot. Putting hot pans down is another concern, though theres probably not any that support that much heat.
If your not keeping with the wood, you could use metal plate, stone/tile. Nice part about wood is that it is basically disposable... if it gets worn or stain or cracked, 10minutes with a screw gun and its new.
I personally laid a stone tile on the wood table for my smoker. Its not attached or anything, not like its going anywhere. but I can pick it up to clean it if I was ever so inclined. protects the wood to some degree, and it looks kinda nice. The wood was dimensional lumber, not that Im laying my steak on the bare surface or anything, but all the same, Id avoid pressure treated if possible.