That likely wouldn't have helped, because sadly some people still think it's funny to steal the actual town signs. I guess even if they'd sell identical 1:1 signs for a fair price, some people would still steal the installed ones.
Given the fact that a fair price for a real town sign is about 175€ somebody will probably just rob the vending machine, either to get the money or a sign. Maybe a card only vending machine would work but changing the name to "Fugging" was probably simpler.
Someone did set up a tourist shop selling T-shirts reading “I like Fucking in Austria”, though the locals found it a bit undignified. (Austria can be a somewhat conservative place, especially in rural areas.)