7. The Best Story Moments Are Optional Or Hidden
This is borderline unfathomable, as one of the coolest parts of playable character Ryder's connection with a unique A.I. brain implant (SAM), is it allows him or her to watch the memories of their father, Alec.
Such memories actually reveal a pretty huge and incredibly important plot point, yet they're forever hidden behind optional 'Memory points' on the various planets you'll visit, meaning unless you put the time into landing, driving to a marker, taking back off and re-visiting the 'SAMnode' computer, you can completely miss them.
This extends to everything outside of the basic 'Fight the evil Archon' setup, as squadmates have multiple specific asks and loyalty missions, yet they're all optional. There's nothing inherently wrong with making the player feel rewarded because they wandered off the beaten path, but when the most essential character-building dialogue and protagonist backstory is missable or gated behind collectibles, that's a big problem.
Speaking of the Archon...