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?