Why haven't they ever made it so that Xbox, Playstation, and Nintendo can all play together online? I understand that there are issues such as competition and hardware, but they should realize the convenience of that.
Are you serious. One, the systems are totally different so certain console users might have certain advantages due to the hardware there using. Two, the console maker want you playing there console, they don't want you been able to play against other people on different consoles, it defeats there objective of selling as many of there consoles as possible. Three, the only decent console online platform atm is Xbox Live, a new unified network would have to be created to support each different console; there would be arguments in who would controll this network. This would be difficult to achieve and different game developers would have to use different netcode in each version of there game to connect to the network. It wouldn't be convienient at all and would be very hard to impliment,. But atm Microsoft is developing a way for pc gamers to play against xbox 360 gamer on xbox live.
Well one, if it's a multi-platform game then when people are looking at systems to buy they won't look at something that is on everything; they will look at things like Halo for the Xbox, Gran Turismo for the Playstation, and Zelda for the Nintendo (not to familiar with Nintendo only games). I play Xbox Live, on Halo mostly, and I plan of getting a 360 soon instead of a PS3 primarily because of the Halo series and the over-all better online set up of Xbox Live. Besides the responsibility for compatibility will probably be laid upon the game developers and the game's server software and format. However the rest of your argument is creditable.
The online game that has done cross platform is Final Fantasy XI (PC and PS2...and 60 now i think?). I'm only assuming that all the characters are on the same server or whatever though, as wiki only says 'first cross platform MMORPG ever'.