Expansion packs are usually seen as a good thing for MMORPGs. Hey, more stuff is good, right?
Well, not always. More is not always better - sometimes it's just excessive.
First off, just to get the obvious out of the way, yes, expansion packs (usually) are popular. They bring a lot of new content to your favorite game, they keep things fresh through adding new classes, they can even add an entirely new graphics engine to keep the game looking shiny. And of course from the standpoint of a game developer, a new box (or "SKU", the gaming industry term for a new boxed release) keeps the game on store shelves well past when it would otherwise be pulled for the cardinal sin of being over three months old. More boxes on the shelves, after all, mean more customers in the servers.
But there are some side effects. Below you'll find a few.
Piling on, not fixing up
Expansion packs tend to be the most polished content in any given MMORPG. This is because as the years pass, the tools used to develop the game improve, and the content developers become better at using them. Programmers learn new tricks in how to eke more performance from the servers.
Yet this generally doesn't trickle down to the rest of the game. Which is not only unfortunate for the people who aren't playing in expansion areas, but also dangerous, because for some strange reason the oldest, least polished areas are the tutorial "newbie" areas that players first see when playing. You can't redo first impressions, and if a player's not having fun when they start, they're probably not going to stick around long enough to see the shiny new areas.
This is addressed to some degree by games that introduce new "vertical slices" of content that allow new players to begin in a newer, more polished area and see the game at its best. However, users who have already maxed out their characters and want more content for them tend to resent development time being sunk into gameplay that they'll never use.
World of Warcraft is taking an interesting tack to this dilemma with their upcoming expansion, Cataclysm. Essentially, they are taking the weakest part of the game - the original zones that the game shipped with - and doing a massive 'do-over', redoing familiar and somewhat tedious zones such as "The Barrens" and "Westfall" and making them over using the improved tools and knowledge that the team has learned since. It will be interesting to see how this expansion is received by World of Warcraft players - so far, they seem excited, and the introduction of two new races, thus giving players motivation to level up yet more characters through the redone content, may help here. Of course, hard core raiders will doubtless finish the expansion three sleepless days after it's released, and then complain about how there's never any new content, ever.
Keeping them separated
One key problem with expansion packs - if you sell them, not everyone will buy them. This results in two problems - "code forks", where the developer has to keep track of every possible combination of expansions that the player may or may not have paid for, and, for lack of a better term, "player forks," where players may find themselves locked out of content their friends are in because they haven't bought the expansion. From a purely financial aspect, this isn't a problem for the developer because it encourages the player to spend money to be with their friends. From a design aspect, this is a problem because the player may decide their friends aren't worth spending that money on. MMORPGs rely on a high player density for a lot of their function. If there aren't a lot of people around, you're essentially playing a single-player RPG, albeit one with considerably less plot development. Thus, segregating players is a fundamentally bad idea.
One way around this is simply not to sell expansion packs, but instead to give them away for free. For obvious reasons this is not the most popular decision among the folks tasked with ensuring the developer remains profitable, but it does happen. Eve is a good example of this; every few months brings a major expansion that is patched out to all players. Older MMORPGs also tend to offer every single expansion pack for free, or as part of the latest one, simply to prevent "code forks" by giving away expansions that they haven't been selling in large quantities, and earning a touch of good will in the process from the few people who haven't kept up with every expansion.
Expanding the definition of expansion
Then there are games that call "expansions" what you or I would call "patches". Darkfall, for example, claims to have had two expansions since they shipped, which is pretty impressive for a game that's been out for less than a year. The habit of Lineage II and Eve to give away all of their expansions for free also could possibly be part of this "expanding patches into expansions" phenomenon, depending on how you view each one. If you're not going to package an expansion for sale, the temptation is pretty huge to just market your latest patch as an "expansion" and add the appropriate bullet point to your marketing materials. Players are usually pretty good at seeing through this hype, and in any event no matter whether you call it a patch or an expansion, the results from either are what is truly important - do they keep players playing, happy, and subscribed?
Oh god, make them stop
Then there are the expansions that players wish never came out, ever. My first experience on MMO server development was for Dark Age of Camelot, on the Trials of Atlantis expansion. To put it mildly, it was not very well received by the players. The designers, many of whom were still enamored with Everquest (the market leader at the time), wanted, among other things, to replicate the experience of massive raids. The problem is that Dark Age of Camelot's players had chosen that game over Everquest, among other reasons, to avoid those massive raids. Whoops. You know when you later release popular servers that patch your expansion out of existence that it may not have been the best of ideas. (And Camelot players, just in case you didn't hate me enough, I was the guy who wrote the code for artifacts. Yes, I know, leveling your pants was the opposite of fun.)
Even if your new expansion isn't conceptually a massive box of fail, expansion after expansion can introduce levels of fatigue that your players just aren't willing to deal with. Take Everquest, which launched with the ability to earn 50 levels. Now, sixteen expansions later, to catch up a new player will have to earn, in addition to 85 levels, a bewildering array of "alternate advancement" abilities which are leveled in addition to/instead of your normal experience grind. Better start now.
Expansions for MMORPGs aren't always a bad idea. Just... most of the time. Except when they're not really expansions. Then they're OK! Except when they're not. Really, it never hurts to forget the official motto of the MMORPG player: "we fear change".
Next week: Please Allow Me To Gank Thee - PvP and how it breaks every MMORPG.