The most important MMOs of the first modern decade
Second part of the most important MMO of the modern decade.
It was, of course, a pioneer in crossing platforms, beginning with the PS2 and PC before adding a third version for the Xbox 360 in 2006. There were and still are questions as to the viability of MMOGs on consoles. However, FFXI led the way in demonstrating that the divide could be bridged successfully, albeit not necessarily to the complete satisfaction of both sides.
That said, while the cross-platform nature of the design was certainly front and center, it wasn't the only reason we had to recognize the game. Another one was its strong art direction. FFXI did a truly exceptional job in terms of creating a world that was not only stylistically distinctive but also where nothing seemed out of place. Everything looked like it belonged there, and the level of attention that presumably went into making this so seemed unprecedented.
Can anyone even semi-seriously quibble with the inclusion of Blizzard's offering in this list? Even before it entered live service, there was no real doubt it would reshape the MMOG landscape.
WoW was able to reach the heights that it did because it was the right game at the right time. The MMOG category was growing and maturing, but the “standard” gameplay of the time was relatively hardcore, even for a fair portion of the serious gamer segment. This meant there was still room (in retrospect, a gigantic amount of it) for a title with, among other differences, a gentler learning curve and overall lower barriers to entry.
I'm not going to debate the relative merits of theme parks versus sandboxes. For some, WoW was dumbed down. For others, it was more accessible. Regardless of our individual preferences, it brought together a combination of play style and other elements that constituted the MMOG equivalent of a perfect storm, one I doubt we'll ever see the likes of again.