Depending on how the server's file operations work, this may be a mistake. When I looked into this a few years ago, most SSDs could only handle about 10,000 writes to a particular sector before the hard drive lost its ability to store data properly, and with a server that number can ratchet up pretty quickly. If they're bottlenecking on HDD I/O operations it might make sense, but it's not a slam-dunk.
Also, W3C isn't exactly made of money. If the choice is between dropping a few grand on slightly better hard drives(since they'll need multiples for each of five world servers, so at least 10 total) or dropping it on dev time to get the game working better, I suspect they'd do better to invest in the devs.