As an omega level mutant, Bobby/Iceman should be a force on the same level as Magneto or Thor. His highest power levels should have been close enough to at least challenge Phoenix. That's what I would expect if someone has an omega level.
I honestly have not seen his powers used at their most optimal since Emma Frost possessed his body. Sliding under a closed door as water and reforming on the other side, merging with a body of water to re-emerge at another point and/or in another body of water, almost limitless indestructibility in ice form. Iceman is an elemental force!
He should get the world endangering Phoenix treatment, but the enormity of his power should be recognized and used as a major asset in battles and extraordinary feats.