Generally speaking, I totally agree with you. However, not everyone can afford a 5-series camera, and one way to lower the price while keeping the features could be to make an APSC version that kept most of the features, but swapped a FF for an APSC sensor. If the pixel density were the same (making it a lower megapixel camera, but "effectively" the same, if you were going to crop a bird from the center anyhow), it could be cheaper. Some of that cost reduction could be actual manufacturing costs, and some of it might just be because maximizing what you can squeeze out of someone's camera budget, and who knows, they can always upgrade next year when they're convinced that a 5 series or 3 series will give them magnificently better photos