Imagine a game where instead of controlling Samus you control her ship and find upgrades for it, navigate in complex structures and rotate freely in 3D. If it were to follow Metroid Prime's first person view it would only feel natural, but the controls would have to be much more complex. Here are a few samples of Descent and Forsaken:
http://youtu.be/DOo-TN-k0CA?t=1m45s
https://www.youtube.com/watch?v=-IzjPPENpdA

