Games don't need to be Retro at all. They should however try to do more in term of gameplay. A game needs to be easy to pick up and play, it should be self-explanatory. If you need a big ass tutorial for your game that bores the shit out of the player for 45 mins, you're doing it wrong. On the other hand, games need enough depth to motivate you for a long time and multiple play-throughs. Easy to learn, hard to master is the magic formula. Many games of the past had such qualities, like Mega Man, Metroid or Super Mario. You can play these and a shitload of other old games until this very day and have a blast with it.
Many, if not most, modern titles lack such well crafted gameplay. Too many times a boring story is presented as the main deal, gameplay falls short. Think about Call of Duty or Uncharted. Sure, first play-through is a lot of fun and all, but would you ever touch those games again? I know I wouldn't. What I'm missing today is the magic that only games are able to achieve. Gaming was always about interactivity. About doing what you want. But while graphics are crushing throzgh the roof, gameplay too many times takes the exact different route. Despite all that hardware power I keep getting messages like "Get back to the battlefield!", "Don't go there!", "Do this and that first!" or some shit. Add some lame cutscenes and I'm bored to death.
Back in the days there was no holding hands. When I wasn't ready for a region in Link to the past or Final Fantasy, I found out the hard way. The games allowed me to do what I wanted to do without restrictions. I could kill each and every civilian in Half-Life, while in HL2 that's not possible anymore. I could kill my own party members in Baldur's Gate or go insane in the middle of town for no goddamn reason. Today's games? Sorry no, you have to follow the script!
Do you know what I mean? I don't feel like the player anymore, I often feel like an actor thatbhas to do everything the director tells him. Even in praised games like the last of us. I want more freedom again and less boring stories. More exploring, more challenges, more secrets. All that stuff. The style of a game doesn't matter at all. If the game itself is good, I'll take it no matter what it looks like. GTA 4 looked insanely real for its time and I loved it. But I also love cartoony games like Mario or something. It really doesn't matter, it's all about the gameplay and I am certain that it's only because of changes in gameplay that games today feel so much different and more and more people like to play older games again.
