I don't think anyone understands this. The S4 is better then the Exynos in virtually everything other then superfluous synthetic benchmarks. In reality, anyone who WOULDNT take a much more power efficient/powerful dual core when compared to a quad core in the mobile space is just inept. I'd be surprised if anything other then some of the multi threaded benchmarks actually used more than 2 cores.
Hell, even Samsungs next Exynos, the 5250, is gonna be a 2Ghz DUAL CORE chip. Quad core is just a marketing gimmick at this point in tablets/phones, although hopefully app developers begin to take the hint about making apps more threaded.