I work for a company which markets internationally, I deal with 17 locales (web sites, software etc.) and Italiano is the least used. we get more traffic/business in Swahili than we do in Italian. This is fairly common for all international businesses. We seen all the arguments for it, but the business reality says otherwise.
Spanish (both Portuguese and Brazilian Spanish variants) is the better choice with a larger user base for MMO's and a growing social demographic.
I'm German, and I don't care about German language support, IMO not understanding English to an extent that you can play an MMO would be a serious handicap for anybody in the world today. But maybe that's just me. In my opinion you should take the money it takes to localize the client and put it into new content (same goes for voice acting)
I just wish they fixed emote "localizations", which have been broken since forever... Why do I need to read someone else's game-generated emote e.g. in german ("their" localization) when my own localization is different?