It's not you, it's me. I can gather enough raw materials from every corner of the world, change my class if I need to better protect against the creatures I'm going up against, and even use a whole set of other skills to get through a tough task set before me. I...just don't need you anymore. In many of today's MMOs, the buzzwords are “player choice”, and in giving players lots of choices, an abundance of skills, and the ability to solo nearly everything, there are tradeoffs. In creating games centered around the player and having endless choices to play “your way”, those tradeoffs can be both harmful to community but financially lucrative for studios. Where has interdependence gone? The way of player choice.
Once upon a time, a popular consideration was whether or not your chosen server would have a good community (at launch or if you joined up later). Would there be a healthy population over time? Would there be helpful, skilled players to team up with? Would there be a good class distribution ratio? And for some, whether there would be active roleplayers (or RP servers). Classes and gameplay and choice were all important, as they are now, but somehow it seems like for myself and most people I know that have played MMOs for a while, the mindset of planning was with a more group-oriented mind. You didn't want to roll on a server with a severe imbalance of, say, mages, making groups hard to find. Nor would you want your home server to have just a handful of crafters. Designers too knew that there was potential for wildly uneven numbers at times, but communities sprung up and often took care of themselves. That's not a rose-colored glasses statement, as having to reroll a character was more painful then, so knowing the community composition and being able to settle into your groove mattered.
Nowadays we have gained more flexibility, which is a good thing. We're able to decide how to play and get in our time without needing to wait around for say, a doctor to buff someone, or the players of one class or race that can gather materials to be online in enough numbers for the groups that need them. Class flexibility isn't recent (one of my favorite implementations actually came in The Matrix Online, where you could actually load up any skill in the game as long as you had unlocked them and had copies), but the whole process has become streamlined in such a way that saves us time and lets us get right into the game. We can also change classes according to our needs or simply tweak our progression. Games like Rift offer this sort of flexibility, and The Elder Scrolls Online looks to head in that direction as well. Final Fantasy XIV: A Realm Reborn is perhaps the best recent example of this kind of system at work. You can learn on the same character and keep progressing.