Games are going toward using more cores, here's some reasons why:
(1) Current gen consoles only have 3 cores maximum on the CPU they used, so the current ports from consoles are not designed to run on many cores like PC's have in their CPUs. However, PS4 and XBOX720 are both going to have 8 core CPU's from AMD.
(2) The last few games to come out, like Crysis 3, Far Cry 3, Metro 2033, Battlefield 3, they all use a lot of cores now, and we are seeing the playing field level, anyone on here advising you to buy intel cannot dispute the difference in frame rate is less than 5 FPS on any of the games mentioned above at max settings between the 2 you selected. More games are going to be this way...GTA5 is coming in september, it's supposed to be 8 core aware when it hits the ground...you want to play it on a 4 core machine?
(3) If your monitor is a 60 Hz monitor, then your maximum frame rate is only 60 FPS anyway...so the difference between 110.4 FPS and 111.7 FPS is irrelevant entirely...you could spend the extra $90-100 to build an intel machine, and you would never realize the difference in FPS anyway because your monitor cannot display such frame rates.
(4) If your monitor would display the frame rates up to 120 FPS (120 MHz monitor)...the average human eye is only sensitive to about 30 FPS, anything beyond that and you cannot tell, some people are a little more sensitive, but in reality, a lot of them it is all in their head. PS3 XBOX 360 FPS are ~30-35 FPS to give you a valid real world comparison, if those frame rates are good for you, then anything over 30-35 FPS is fine.
(5) Software development always runs about 18-24 months behind hardware, because it takes about 2 years or so to develop a game around current hardware. The Piledriver architecture has been out for about 18-24 months now, and look at what we have here...a boat load of games coming designed around heavily threaded code and 4+ cores CPUs. Coincidence? Couldn't possibly be!
(6) The only advantage the i5-3570k has over the FX-8350 is in SOME games...and frankly...if you do anything other than game...the FX-8350 is a better solution for that...there are benchmarks out there to prove it too. You should also view any benchmarks shown with a grain of salt. openbenchmarking.org actually check the compilers in the benchmarks they use to make sure that the compiler doesn't have the intel "check AMD" flag. Which intel used to slow down AMD CPUs by making the code more convoluted. If you think I am lying to any of you, google it and see for yourself, AMD sued and won in court.