Hm, after having looked through VGC's Metroid sales data (assuming it's more or less accurate) it really looks like the problem is making a Metroid that will sell well in both Japan and the west. One seem to prefer 2D (incl. OM) Metroid while the other prefers Prime.
To make a Metroid that is huge saleswise Nintendo would need to either pretty much ignore one of the two markets and go all-in for the other one (Prime) or make a Metroid that nicely blends both styles (has yet to happen).








