The only reasonable
APS-C advantage is the price. I'm talking about the camera body price only, not the whole system.
Not the reach - because, when both formats have the same pixel pitch (like D800 and D7000), we can just crop the FF image (or shoot in crop mode) and get exactly the same result as if we shot it using a crop sensor camera. I'm not a big super-telephoto fan, but my first 4 DSLRs were APS-C, just because I couldn't afford FF. If FF sensor production becomes much cheaper, then I don't see any reasons to keep APS-C other than for mirrorless (for "pocket photographers").
Not the size and weight - because of the previous reason, for telephoto you either get more resolution or more reach with the same lens, while APS-C gives you no choice, it is like crop mode only (24/7
). For wide-normal angle, many zooms (like EF-S 17-55/2.8 IS USM) have no advantages over FF competition (like EF 24-105/4L IS USM, which is similar size, similar weight, similar price + even wider focal range, shallower DoF at f/4 than APS-C at f/2.8 + better build and weather resistance) ... EF-S 10-22USM vs 17-40L ... EF-S 15/17-85IS USM vs EF 28-135IS USM.
FPS? It is possible to shoot faster in crop mode. Nikon does that. Canon think that 7D will sell better if they don't include that feature in their FF cameras
So, unfortunately, it's all about money.