The number one reason is, not being interactive like the games they portray.. It creates a disconnect between the game and movie. How many times have you said "wow this is nothing like the game"? The rest are pretty much ways to save money, which can break any movie. Missing the premise of the original story, rewriting essential plot points to avoid expensive locations, sets or effects. Bad scripting with cliche jokes, situations,etc. Cheap fx/stunt gimmicks that wind up looking totally unbelievable. Low budget actors or good actors but in the wrong role.
Google "German game movie scam" for another interesting reason.
So, what do we need, $100,000,000 + budget, good script writers from the team that created the game if possible,directors that arnt just there to get paid, talented actors in the right roles, next gen special effects, A one size fits all way to interactively participate. that doesn't add to the price of the movie ticket, DVD, stream, etc.