I can't exactly agree that Metru is predominant though, seeing how it only existed for a year, which is something that even the Toa Mata build exceeds. But that's just a nitpick
As for the point of this discussion, while the Inika/Piraka builds are considered to be the standard for how the action figure is supposed to pose, there's a major grievance that I had with it ever since 2007 - proportions. It shows up the most with sets like Hewkii Mahri, Gali Mistika and Mata Nui - basically any set that has arms same length as, if not longer than, the legs. Naturally, it would've been a simple fix of using shorter arms and whatnot, but the discussion is about what happened, not would could've happen (even if it was, both torsos are disproportionate, both is short height and great width).
While, in other hand, the Metru build actually looks humanoid (though I'd want the arms to be just a stud longer). Sure, you do have the unfortunate inability to turn gears independently, you do get a more refined aesthetic, realistic humanoid proportions and a bit more creative playground, seeing how there's a bunch of things one can do to add a bit of a special touch, where as pretty much anything you put on an inika build makes it seem too bulky or too awkward to function on good days, if not straight up misshapen/not fit for a stoic hero character archetype.