My guess is that it wasn't fun because he was probably playing a golf course designed for the aerial, spin-control game.
Agreed...I don't know what course he played when he did this (unless the article mentioned it and I missed it).
Stewart Cink, like most PGA pros, probably defines golf as "my job, which requires me to shoot the lowest score possible". If he suddenly cannot spin the ball as much, and went out and played in a vacuum (not against competitors), in his mind his job just got harder which is not fun.
Or maybe golf is just not as much fun when you duct tape your clubs. If indeed you get NO spin when you duct tape your clubs, I'm sure it isn't as much fun. You've got to be able to control your ball a little, if all you're hitting is knuckleballs then you can't move it at all. I have to be honest, I've never duct taped my clubs so I don't know how dramatic the effect is.
A friend of mine used to have a "Duct Tape Man" costume that he wore on Halloween several years in a row. It was a full-body superhero outfit, constructed entirely of duct tape. Every year he added a new accessory - cape, mask, shield, sword, etc. It was pretty impressive.