>>8989131This is just my assumption though, but Bandai (Japan) as a toy company has to always sell new things. You know/ever heard those capsule/gashapon SD Next/Dash/Forte? Each lines always has RX-78-2 and Char's Zaku with different designs in every few years.
And also I guess Bandai is experimenting on selling an inner frame figure and an armor figure which push collectors to buy both as a set, especially those from the kamen riders.