Not really. Clutchless shifting, if performed properly, doesn't
damage or wear out a manual transmission gearbox any more than
regular shifting does.
The key is to acquire the finesse to be able to match revs between
the engine's output shaft and the transmission's input shaft for a
clutchless shift to be performed properly.
Sometimes, when I'm crawling through heavy stop-and-go traffic,
I'll occasionally shift without using the clutch as I'm too lazy to
move my left foot. 
