[Shin Henshin]

Even if Fever is a transition form into something like the Command buckles, it's still a form that 1.) some collectors would honestly want and 2.) give more options to the revolve change gimmick the SHFs already have. People are gonna want Boost Magnum, so why not make it the Fever release to kill two birds with one stone and get sales for extras from people who may wanna display all the combinations.

It's no different from how they released SS Den-O Plat Form and then rereleased it with retooling and some extras so you have to buy one of each type to display all four main forms.