Game development (for mainstream or popular games) is a very pricey endeavor though. It's not uncommon for development and marketing costs combined to hit close to or over $100 million. So naturally they're going to be reluctant at trying out new things for which there is a very possible chance it will totally flop. As much as I like originality in games, I'm not going to hold a grudge against devs or publishers that make barely any changes to the gameplay formula and stick to something they know is lucrative (many modern military FPS games and Assassin's Creed series for example). They are a business first and foremost after all. Indie games and smaller studios are usually where the more 'artsy' or creative/original games are.
Maybe I made it look like I want every developer to make revolutionary game design. But that's not what I meant. I like when they bring at least some changes to gameplay and listen to what faithful fans of a franchise have to say. And indie developers because you never know what kinds of new things they can bring. But I agree, many times they just can't risk new things.
Like you mentioned, some shooter franchises change almost nothing but graphics and physics technology from one game to the other.
But I still have lots of respect for what CryEngine or Frostbite can do, and what DICE and Crytek have accomplished.
Some people criticize COD for being repetitive, but I find the plots of MW, Black Ops and Advanced Warfare very good.
I just prefer to spend money on games that bring more new elements and avoid just copying some formulas, they just
spark my curiosity more. Maybe it's because of my age. After some time, I see some gamers care more about new gameplay and artistic concepts and story telling more than realistic graphics.