That's sort of the FCC's fault; it's very hard to get a high-bandwidth device certified under FCC regs (e.g. part 15) if it doesn't have a locked-down processor that controls radio functionality. See this article about the FCC intentionally/unintentionally locking down Wifi routers due to licensing requirements: https://www.wired.com/2016/03/way-go-fcc-now-manufacturers-l...
I'm sure if it were up to apple they'd be putting high-level radio functionality in the main CPU. It's cheaper that way, and matches with Apple's security/privacy-oriented marketing.
That's also a typical concern about baseband processors - and Apple has a baseband processor integrated into their iPhones and iPads. OK, there is a difference: While for ethernet ports (and with a little bit more effor WiFi connections) you can at least theoretically analyze whether there is dubious traffic, this is nearly impossible for connections over mobile networks.