I liked the original Rahaga sets, but messing with them now I thought their lack of articulation was a shame. Happily, that’s not much of a problem here. Shoulders and elbows, oh my!
It looks to me like the Rhotuka Launcher hinges on one of his shoulders, like how the Bohrok Va’s krana holders were linked to an arm. Is that correct?
The Rhotuka launcher is connected to both shoulders, and actually serves the purpose of keeping the balls in place. It sadly can’t hinge because the flat bottom of the launcher prevents it from flipping up against the main body part. To fire forward the neck must also lower, as in the last picture.
I’ve always thought it was because Lego didn’t want to include the piece in multiple colours in the same set, or perhaps just because they didn’t want to include another unique piece.
(Admittedly, that first theory is somewhat undercut by the fact that the socket piece is included in two colours in all of the sets besides Bomonga.)