I am enjoying the new resurgance of indie titles that want to capture the charm of old sprice based games.
But there is another reason what they are being more common today.
The people who grew up with pixel graphics games.
Today these same people have enough resources and knowledge to make a game and decide to pay homage to what they enjoy. Or in a more cynical perspective, they're trying to cash in on successful pixel graphic styles.
The thing is, many AAA games already focus on realism in graphics.
Indie devs are often times single developers, or small teams. They have absolutely no way to compete on the realistic graphics front with AAA titans like EA, Ubisoft and the like. Why bother with trying to make a 3D game and make it look like it's from the Playstation era, when you can actually create beautiful sprites and backgrounds in half the time?
It's cheaper (under the right circumstances), conveys the game mechanics just as well and looks far better than what they can do without a dedicated animation department.
It's also important to note that 2D worlds are far easier to code, since collisions can be far more precise and easier to predict. It's also less resource-dependant, which is crucial for indie games. When you create a product that's niche by design, why reduce your audience even further because of high system requirements?
It's also because of the tools that became available to the general public.
It's really easy to make a good 2D game using Game Maker, Multimedia Fusion or Stencyl, all of them free to use (or with free versions to try before buying). 3D is starting to slowly catch up (especially thanks to Unity and the new Unreal Engine), but they still have a way to go.
Doesn't mean there aren't those few who make more cartoony aesthetics, just like there's some indie devs who aim for more realism, but that just tends to be the trend.
Personally, I'm just thankful that the trends are slowly moving away from 8-bit imitations to 16-32 bit ideas.
Some might seem silly, but there's genuine art and talent behind a really good, well animated set of sprites. There's a certain artistic charm to it that's just lost in 3D a lot of the time. I'm a big fan of the approaches of WayForward or Lab Zero Games, who opt more often than not for hand drawn looking animations in lieu of pixel graphics, which hit a great middle ground in representing cartoony/fantasy places, while still making use of advanced technology.
I'd argue it takes a hell of a lot of skill to have high quality, HD hand drawn animations, even if it's not exactly breaking your processor or aiming for realism.
But, there are some who do use retro graphics for convenience instead of a deliberate art style or focus.
I hate the phrase, but sometimes it really does depend on a game by game basis. Does the developer want to evoke a certain style and feel that pixel graphics are best to represent it, or do they have limited budgets and prefer to focus on fine tuning the gameplay at the sacrifice of visual fidelity?