bringing piccolo to namek was retarded.
The whole reason they went to Namek was to use those dragonballs to wish Piccolo/Kami back to life...so lets bring him to the planet with the strongest mother fricker in the universe even though Piccolo recently got his arse handed to him by a guy 1/1000000th of Frieza's power.
Wishes that would make more sense:
1. wish for an unlimited supply of sensu beans
2. wish for goku to be immortal
3. wish for Gohan to be ~6 years older