You can't pretend to offer the best consumer computer infrastructure/integration with a wireless router NOT in the lineup. I can see express and time capsule as gravy, but a wireless router is the bread and butter for today's wireless home.
My fear is that Apple marketing department will use this "hole" in the Apple universe to force us to buy some other product (e.g. Apple Speaker) to get the wireless router functionality. Artificially boosting sale of target device by force....
IMHO it's because they didn't want to get into the WiFi mesh business and compete at preset prices. While I still think that Apple offers an unparalleled eco-system if you're an Apple home or even partially Apple google's is more complete. Chromebook and box/Google WiFi/ProjectFi/Android/Cast really has all your bases covered with the obvious caveats.