I agree that the ending was somewhat less than satisfactory. It's not made clear why the death of AU313/Dark Samus should destroy Phaaze, and it's certainly not clear why we should believe the outrageous idea that the death of Phaaze automatically destroys all Phazon in the entire galaxy or even the universe. The true origin of Phazon is not explained either, which is something we were promised. We are left to conclude one of two things:
1) Phazon arose naturally and is part of the natural universe. In this case, I would highly suspect that Phaaze is neither the only nor the original Phazon world, but only one of a chain reaching across time and space.
2) Phazon was an engineered substance, perhaps created by an ancient race as a bioweapon, and got out of control, taking over the entire planet and then spreading itself. Phaaze is likely the original world.
In either case, it's reasonable to assume, given the thousand some odd years the Chozo knew of Phaaze's existence, that hundreds if not thousands of other worlds were corrupted in that time frame (Tallon IV and Aether were corrupted within only a few years of one another). I think the idea that they're all now magically purged of corruption and healed back to their natural state is silly and requires metaphysics to explain. The only reason they added that element to the story is so that they can be done with Phazon from now on. The Prime series ended up elevating Phazon to the status of a god, and then it has to kill its new god in order to move on.
I think a more open ending would have been better, as well as an escape sequence. Prime 3 is missing far too many Metroid elements, and that's one of them. After Prime 2's ending, I figured it was a given. Unfortunately Retro was convinced that everything they did in Prime 2 was wrong, apparently.
1) Phazon arose naturally and is part of the natural universe. In this case, I would highly suspect that Phaaze is neither the only nor the original Phazon world, but only one of a chain reaching across time and space.
2) Phazon was an engineered substance, perhaps created by an ancient race as a bioweapon, and got out of control, taking over the entire planet and then spreading itself. Phaaze is likely the original world.
In either case, it's reasonable to assume, given the thousand some odd years the Chozo knew of Phaaze's existence, that hundreds if not thousands of other worlds were corrupted in that time frame (Tallon IV and Aether were corrupted within only a few years of one another). I think the idea that they're all now magically purged of corruption and healed back to their natural state is silly and requires metaphysics to explain. The only reason they added that element to the story is so that they can be done with Phazon from now on. The Prime series ended up elevating Phazon to the status of a god, and then it has to kill its new god in order to move on.
I think a more open ending would have been better, as well as an escape sequence. Prime 3 is missing far too many Metroid elements, and that's one of them. After Prime 2's ending, I figured it was a given. Unfortunately Retro was convinced that everything they did in Prime 2 was wrong, apparently.