2. Don't Reinvent the Wheel
Perhaps the biggest thing that Masters '87 failed at was that it had all the elements of a great He-Man story in place and then bungled them so badly that it was almost unrecognizable. The plot alone is brilliant. Skeletor has finally taken Castle Greyskull, the Sorceress is held captive and Eternia is in a state of war as He-Man and his Masters of the Universe have formed a rebellion to recapture Greyskull and defeat Skeletor. YES! That is everything He-Man should be! So what went wrong? Well, a lot of what went wrong are the previous things on this list. Moving the action, and the champion of this rebellion to another planet is a silly thing to do. Ignoring the things that made the animated series successful while trying to cash in on the success of the same series is ridiculous. The film sought to tell an original story in an established world. That's fine in and of itself, except that the filmmakers got it all wrong. Chiefly this was in the source of Greyskull and the Sorceress's power being the "Eye of Galaxy." Greyskull's power was always locked away, known only to the Sorceress and stored in the Castle by the Guardians of Greyskull. This "Eye of the Galaxy" reinvents not only key elements of the established world, but it also changes the origins of He-Man himself. There's no need to reinvent the wheel. In this case, as in many others, it only served to confuse the audience. A successful reboot has plenty of source material to draw on, and would have no reason to try and retcon, or otherwise reintroduce established elements or characters with changes.