Back when I first started gaming, there were many books and articles talking about different player types like the min/maxer, the rules lawyer or the thespian. Many of these described personality traits and others referred to styles of play as well. We sometimes used different words of course but these were usually types of people everyone knew from their own groups. It was pretty normal to have a wide range of player personalities and styles present in a single campaign, with the GM needing to accommodate them all. Increasingly it seems that there is a lot more interest and discussion in having groups that are largely homogenous. I am not so sure this is a good thing.
This may simply be one of those things that happens online more than in real life. I am not sure, because while my own groups are fairly diverse, I also am aware of changes in the direction I describe locally in my area. And if people want to seek out players who match their own style of play, it isn't like there is anything wrong with that, I just worry that too many of us are embracing this approach when we might benefit from exposure to other tastes and preferences.
I am sure many of you are familiar with the Malcolm Gladwell Ted Talk Choice, Happiness and Spaghetti Sauce. If you haven't seen it, here is the link: MG TED TALK. It is actually a really great presentation and it has some obvious connections to play styles in RPGs, so it often gets mentioned once or twice in online discussions about roleplaying preferences. I think there is some truth to that. We all have our own preferences and it can be a good thing to find the common set of tastes and create games around them.
However, there was always something that troubled me a bit about the Malcolm Gladwell talk on spaghetti sauce. Those three options are great if you are the only one eating the sauce, or if by luck everyone at the table shares your preference for chunky. I grew up with an italian mother who made sauce at least once a week, and it was always shared by 4-10 people (a bit like a roleplaying game). She had to consider everyone's preferences and make sauce that we were all willing to eat (and we had to return that courtesy). I do like my sauce a bit on the thin side, but one of my sisters didn't, so the result was a compromise that still tasted delicious. I think in gaming it is pretty similar. Gaming is more like that.
Now I am not saying people shouldn't design focused games. I like focused games once in a while. I think they serve an important function in the hobby. But I am saying you shouldn't limit your dinner company to those who share your tastes in tomato sauce. This isn't so much about game design as it is about how people choose gaming groups. Play with people who like different things than you do. If you are a GM, it will expand your repertoire and open you mind to different approaches. If you are a player, it will get you to try different things.
In my groups I play with all different kinds of people. We have players who get really into character and like systems like Savage Worlds. We have players that enjoy exploration and a dose of realism, and prefer games like GURPS. We have players who are into story, tactics or power. I have one player who really likes Dungeon World, another who really likes 3E, and another who can't get enough of old school games. I also have players who are newer to the hobby, whose tastes are evolving as they play.
As a GM, I am pretty accommodating. While I have my own preferences, and I try like when people share them, I also am quite at home running a game for groups united by a love of optimization, monty haul, or tactical play. When I was younger, I resisted styles I didn't like. I didn't attempt to understand players who had preferences I did not share. Eventually I realized there was a lot to be gained by running games outside my comfort level.
When I look back at my groups, without question my favorite campaigns involved players who represented a mix of styles. Not only did it produce better gaming, but it also created a much more enjoyable social environment.
This does mean as a GM you have to weigh the needs of the many. You can run what you want, how you want it, but how successful that will be depends on a certain degree of flexibility and your ability to customize the game to those present.