I'm sure a new Metroid would sell very well, maybe even better than Bayonetta 2 and Hyrule Warriors combined, so I'm actually pointing the finger at Nintendo for why they haven't done anything about it. (Especially since Nintendo needs a good FPS and Metroid Prime was a spectacular show to its fans that they too can make a great FPS...)
Honestly if I had to think of a logical reason as to why there's no new Metroid (yet), I bet it's because Nintendo is afraid the series might become stale and repetitive much like any other FPS out there today. (You could argue about Mario being repetitive all day you want, it still won't take away from the fact Mario is their bread and butter, so the only option is to suck it up... As unfortunate as that is, it's the truth.) :/
