The idea sounds nice, but I'd say that they should be left for players to find. @qazini said what I first thought: anvils are a great way for /pwarps to provide a service to attract players. A change from players to the server providing services should be in a way which allows the service to still exist, or players are left with less things to do. This same logic could be used with enchanting tables and ender chests, which would cut out all of these simple services many pwarps provide.
I like the idea, but I don't see a good implementation to protect shops. If one is provided, then I might change my mind.