It was too costly to maintain the spinning planet effect because the motors are at angles and that angled motion causes them to wear out quicker. That's just what has been passed along.
Back about 2004 or 2005 the planets were refurbed and many were not spinning then. There were motor repairs and/or replacements at that time for all the planets and I thought were spinning until the recent closure.
Thanks for the replies! Seems strange that they didn't fix the planets if it was just a matter of broken motors. I've seen car washes with spinning advertisements that look more complex. I'm sure the company that literally builds mountains could have fixed it if they wanted to. Unfortunately we all know a broken motor is enough for TDO to justify pulling the effect . Not to sound all negative though, the refurb has certainly given Tomorrowland some glamour.
I love the new paint scheme. It really brightens the place up and draws your attention. Almost makes it feel more alive. Hope they get those planets moving again soon.