Why were the original cast of Mighty Morphin' Power Rangers, so upset?

I read everywhere that Thuy Trang, Austin St. John, and Walter Jones were all upset with the hours and the poor pay. Also, Amy Jo Johnson complained of having to do all of their own stunts due to lack of stunt doubles (may have been for the movie). However, most of the footage in the TV series was taken directly from Japan's Super Sentai/Zyuranger. Scenes with the Zords, monsters, and fighting sequences have been taken from Japan's shows for the duration of most Power Rangers series. So what was really going on?