5. Easier And Less Costly Development
This might be the most up-for-discussion point in the whole list. While an easy game does not guarantee small development costs, it is of great importance. Designing complex mechanics takes time and money, and implementing them successfully takes even more of both. Throw in a story long enough to complement these additions, and you've already spent mighty dollar on a game people might or might not understand/appreciate/buy. How do you counter this? Just don't make it deep, complex or expensive. Make it look cool on the surface instead. You save time, money, and can also make it appeal to the more casual base -- why not? After all, there's no shame in saying you're in for the money -- people got families to feed, that's completely understandable -- the shame is when you try to apply a coat of sugar over it. I might be the only one, or one of the dying breed left that plays Call of Duty for the campaign. What once was a spectacular, epic journey through war has now devolved into a corridor shooter. The blueprint of corridor shooters, to be exact. Sure, stick with the successful formula, you'd be a fool to tinker too much with it! But the use of the same old engine over and over again limits an already lack of creativity from Infinity Ward/Treyarch's side, as it limits what they can do with the game.
Example: Hordes of licensed games