When I started playing MMOs and other online games, I was very much an elite gamer. I sacrificed hundreds of hours of sleep and study to pursue my goals of being great at playing the games I loved. I beat certain games over and over again until I could conquer them in my sleep. I saw failing at something as a challenge, not a reason to give up. It was a very different time in gaming, and the stark contrast to modern days is interesting.
Casual today is a buzzword. It means playing Candy Crush instead of Halo. It doesn't have anything to do with the time commitment (my wife has put way more hours into a casual game than I have to any of my "normal" games) but skill level. These games are easy, reward you for doing simple things and playing constantly. They offer easy ways out, to buy your solutions. I don't even really see how it can be fun to just buy your way out of your problems in a game....after all you are investing time to enjoy it so why pay to skip parts?
Then I think about MMOs that exist today. WoW has gotten progressively easier as time has gone on. Sure, there are still challenges, but more and more of the game is user friendly, the learning curve is less steep and a child could (and regularly do) play the game. I've seen raiders who were very young excel at the game (like my cousin's 5 year old....scary thought). The flip side of this is that it takes longer to get the best stuff. In order to keep you playing, WoW now (and for some time has had) long faction grinds (nothing like the original ones, though) that are more or less mandatory for raiding. Everythign is keyed to your gear score, but you can go in the kiddy pool (LFR raids) if you want a lot earlier.
I don't like this trend towards easy gameplay, but large time investments. I like deep and immersive games where you have to puzzle and figure things out over time. The EVE online learning curve is the game I want, where things are easy to start but super difficult to master. I like games that keep you guessing, that require you to use your brain and not just show up. However, I firmly realize that i am now in the minority of gamers. Too many want flashy colors with no content. Its like a cupcake, it is the sort of thing that is nice, but if you eat only cupcakes, you get no real nutritional value and your muscles and mind waste away while your waistline grows.