Somebody anonymously posted a question to me in a comment thread which didn't quite belong there (Hint: you can send me an e-mail). But as the question is interesting enough, I'll copy it to here: "I know this is a tad early, and you did mention you getting into it later on this year, but I was ondering what your initial impression with the sudden wave of MMO's coming out? I remember when if you had two MMO's coming out within a year of each other, it was considered flooding the market. But with a WoW expansion, WAR, LOTRO, another Guild Wars expansion and (the one I cannot wait for) Age of Conan, we are experiancing a veritable golden age of MMO's. We now have so many options within this once niche genre that the consumer is able to enjoy a more specific game type, able to cater to a specific audiance. Now, is this just an inflation we are experiancing for a short period of time, or will we be able to sustain multiple MMO's on the market at the same time because of an increase in the size of the consumers?"
My take on this is that what we are experiencing is a mix between viable new games that will survive due to the much increased market, and not-so-good me-too games and niche games, which will either fold or just survive near to the break even point. And I think it is safe to say that World of Warcraft is somewhat responsible for most of them, good and bad. I'm not saying that if WoW hadn't come out there wouldn't have been any new MMORPGs, but certainly a lot less.
The games industry works pretty much the same as any other industry. Take a typical example from another industry, lets say the car industry. A couple of years ago only few car companies offered SUVs. But then SUVs became more and more popular with urban buyers, and the companies making SUVs made huge profits. So the other car companies started offering SUVs too. For game companies the first MMORPG breakthrough was Everquest, which lead to a first wave of "second generation" MMORPGs, with different degrees of success. Personally I consider World of Warcraft to be last one of this second generation, Blizzard being a bit slower than the competition, as usual, but making more polished games. In any case WoW was the second breakthrough of the MMORPG genre, leading to the next generation, we can call it the "third", of games. This nicely coincides with a growth in broadband internet connections, making the growth of the market possible.
As I said, this is mostly a business phenomenon. World of Warcraft probably made more money than any previous PC game. An executive of any other game company would need to be blind and stupid to not even consider trying to reproduce that sort of success. And suddenly there are not only bosses in game companies, but also venture capital companies willing to finance this sort of game. If you were a game developer with a small independant company trying to develop a MMORPG you might have gotten a lot of doors slammed into your face before WoW, but after WoW suddenly your phone started ringing all day. So if you suddenly got investors in early 2005, and given the 2+ years it takes to develop a game, the "wave of MMO's coming out" in 2007 and 2008 isn't so surprising. That includes games that have been under development since before WoW, but got sudden injections of cash to speed them up or make them bigger. EA buying Mythic for Warhammer Online is a typical example of a game company giant wanting a piece of the pie, and buying in the expertise from a smaller company with a good track record.
In terms of gameplay and design, the "third generation" isn't as clearly defined. A game like Vanguard could as well have been part of the second generation in terms of design, having a distinctive "pre-WoW" feel. But games like LotRO obviously profited from the development of the genre by WoW, and apply the lessons learned from that game. And then there are other games which reacted to WoW by trying to differentiate themselves from it, for example by covering other genres than fantasy, while still trying to profit from WoW's success and growth of the market.
In all that Sturgeon's Law applies, 90% of everything is crud. But even if only 1 out of 10 MMORPGs is good, an influx of cash into the genre leading to more games being published is still increasing the total number of good games, even if they appear to be swamped by the much bigger number of bad games. And some of the 90% "crud" games aren't so much bad as niche, only being interesting to a much smaller audience. And that is a good thing too, we are better off if not all games are the same mass market style. The growth of the market allows smaller games to survive, even if they are far from reaching the success of World of Warcraft.
So whether you like WoW or not, I think over all it had a positive influence on the viability and growth of the genre. MMORPGs becoming "mainstream" certainly has some disadvantages as well as advantages, and not everyone will like it. But our chance to find a good game that we like, niche or mainstream, has certainly gone up this year. That can't be bad.