Mainly management issues. Time constraint. See, some games, like those successfull indie games, are passion projects. Often forged by one mind.

Big companies hire people for a project. You see an issue with gameplay? Too bad youre just the designer, no one wants to hear your opinion. You lose passion, if you had any to begin with. Then companies tend to see workers as slaves. Bend the knee or else. Id not go the extra mile for benefits barely matching the lawful minimum. The new avengers show will drop nxt year? Gotta ship a product which normally needs years of development. You cut features to meet deadlines. Sometimes this is also because management thinks only pressure makes people work at all.