You just used the word "industry", so the answer should be immediately obvious: money.

Being creative doesn't guarantee food on the table, but following trends and formulas that lead to sales, does.

You'll always find the occasional indie "artist" or "dreamer" who tries to make something creative, but either they get very lucky and the game becomes a surprise hit, or they quickly realize that if they want to survive they'll need to follow what's working in the industry... or find a different job altogether.