Actually I don't think mouths opening is too hard for Bandai of America to do. Even their Samurai "Folding" Zords have movable mouths (one of the few "initiatives" taken with moving parts).

I'm of two minds on this. On one side I'm bummed about the lost features and details from the originals. On the other hand these are made to handle rough play, not to showcase in a fancy room.

But on the topic of Headers they may be able to squeeze in the bulk of the what made the DX Goseiger mecha so popular but I'm not so sure.