You can't judge the overall appreciation of a console determining it off of exclusives, for that debate just turns to a quantity bias a majority of the time. The reason I feel the Xbox 360 is leading the industry is because of three things. Enjoyable games, enjoyable online/multiplayer/, enjoyable replay ability. The Halo series is a correlation of games that really speaks for the core Xbox players. It really shaped, and engineered the way we actually play Xbox today. Being that Xbox Live is practically limitless in the world of multiplayer, hours and hours can be spent on the console with still an enjoyment factor, that I feel the Wii, and Playstation lack. Being Xbox Live is probably the most renown online community of the three consoles, it develops new, intermediate, and experienced players into a very large, and intact community. Games like Halo, Call of Duty, Gears of War, really created Xbox into something very large, along with many, many other single games. Being so, game developers will generally lean toward a console with better profiting, and publicity. While Grand Theft Auto was a Playstation exclusive since the start, being they went multiplatformed it obviously let them consume $500million+. Playstations network may be free, organized, and casual, Xbox Live let's you play how you want to when you want to. Deeming every game produced for the 360 is generally able to interact with Xbox Live, whether it be for multiplayer, or extra content, it really pushes gamers to stride towards Live, and communicate with the community. Along with the fact it's much larger then the Playstation network, players have many more interactions.
BioShock was an Xbox exclusive. I personally don't care, because the PS3 has functionality, while the Xbox has playability. I'm still waiting for a game that can play multiplayer on Xbox, Ps3 and PC in one lobby