The FX-8000 series vs the i3 is kind of like that "Haha intel beats AMD at every price segment!!!!"
Ya, the i3 may beat the FX-8000 in a lot of games, but would you really want it over the FX-8000? I think the performance lead of the i3 isn't that large, but the benefit of simply having more cores for background tasks is great.
Who actually turns off EVERY process before gaming? I don't. I may have 150+ tabs open sometimes, and some of those tabs eat up processor cycles. With 30 tabs open right now on my C2Duo machine, I'm at 25% cpu usage. Flash video, ads, whatever eat up CPU usage.
I'd rather have an FX-8000 series processor where I know I have 2-3 extra threads unused while gaming that can eat that up, rather than an i3, where I need to shut everything off to get that extra performance. At that point, do I really care if I always have to exit every single application before gaming?
The i3 is like the GTX 770 2GB. It benches nice, but I still took an AMD GPU with more VRAM for the longevity. GTX 770 owners are upgrading, I'm not as my GPU still runs well due to more VRAM.
For me it's:
Pick up an FX processor on sale and OC
i5-4690k
i7-4790k
i7-5820k
Those are my favorite value picks.