Because none of those things are necessary for the transformation. You can keep the other shield on, you can choose one face plate, you can leave the gaps in the legs (like on the yf-19)... Those are extra parts where as on the hi metal version you need to take parts on or off to actually transform it. That's a big difference.
It looks to me like the intake covers are an insert but maybe the mechanism that allows the LERX to slide down is occupying the space that would have otherwise been used for the intake detail. If that's the case, I much prefer the correct leg position.