There is a difference between resonating and working. The resonance causes the fibers of the wooden instrument to actually weaken, but in a way that enhances the desired vibrations. This works well with the thin wood in the body of a cello, viola or violin. But the opposite is true of the heavy sounding board of a piano, as I'm sure our piano expert, Snag, will confirm. Pianos sound worse with age. Bows are involved in heavy work and violent vibrations that will tend to cause deterioration with age, especially in self bows, which tend to have fairly limited lives with extensive use. Bows reinforced with glass and plastics hold up better.
Allan