I played through the game on Normal mode and managed to complete all the Optional objectives and gained the "Good" Ending (including the Jean Grey becomes Phoenix part). Playing through Hard mode, I decided to avoid all the Optional objectives and try to get the bad ending. So I ignored the cage with Senator Kelly, I left Odin locked up, I chose to save Jean Grey, etc...
HOWEVER, at the end of the game when Uatu shows me what effect my actions had, I got ALL the good endings again! Including "You should have saved Jean Grey blah blah blah". What happened? I even checked the videos section and Destiny 1 & 2 are exactly the same. How can I see the world come to an end and all the sad mistakes I made. I definitely don't want to play through the whole thing a third time.
That is weird. Try it again and this time save Kurt and START the side missions but fail them (like saving the Omega Base, saving Namor, etc) and ignore the rest (ie. finding Ultimate Nullifier,etc) and see what happens. This has never happened for me but if you didn't already know the scene with Volla's Ring is messed up. The audio will always be "good" but if you didn't give the ring, you will still see the bad ending. Turning on subtitles will let you know what happened in the bad version.
Other than that, no problems.
"Trust me... I know what I'm doing!" ~ Sledge Hammer