It's funny that the Celerons you call expensive make up for almost all the processors in cheap laptops such as Chromebooks which sell around the $200 price point[1]. Heck I bought one of those Kangaroo portable desktop things[2] last week for $100 which has a dual core Atom.

Now maybe Core M was an especially gimped CPU but it might be a part of Apple's strategy to push users from entry level Macbooks to the iPad Pro. But all of these other devices with Celerons / Atoms are really capable and people use them for actual work instead of using an iPhone/iPad despite what the benchmarks say.

[1] http://www.amazon.com/gp/product/B00MMLV7VQ [2] http://www.engadget.com/2015/10/26/infocus-kangaroo-pc/