To be fair do the hardware vendors and the Qubes team, the certification requirements are disclosed and the bar is already pretty high.
Regarding USB controllers, the only requirement is that there is a way to have mouse /keyboard in a dedicated controller or PS/2 directly. Quoting from the certification requirements:
Most laptops use PS/2 connections internally for their input devices (i.e., keyboard and touchpad). On most desktops, however, USB-connected keyboards and mice have become standard. This presents a dilemma when the computer has only one USB controller. If that single USB controller is dedicated solely to the input devices, then no untrusted USB devices can be used. Conversely, if the sole USB controller is completely untrusted, then there is no way for the user to physically control the system in a secure way. In practice, Qubes users on such hardware systems are generally forced to use a single USB controller for both trusted and untrusted purposes — an unfortunate security trade-off. For this reason, we require that every Qubes-certified non-laptop device either (1) supports non-USB input devices (e.g., via PS/2) or (2) has a separate USB controller that is only for input devices.
Even though in an ideal world we have separate controllers for every USB port, this is hard to achieve. If you look under the hood, almost no small/mid laptop vendor has full control over the motherboard design. It’s a complex system and I do truly believe that if if vendors could get these devices with individual controllers at a competitive price, they would. You can see example of some of the attempts and failures of getting even an more frequently requested feature: hardware killswitches.
With that said, I don’t think it’s fair to approach the topic as you did here. It’s understandable that you are unhappy with the device, but (a) the requirements are clear regarding the possibility of one controller and (b) this is an advanced feature that is not critical for running Qubes – in fact, Qubes tries to mitigate USB threats with the USB proxy which in 4.3 will be even more convenient to use. But there is only so much one can do in software.
Perhaps a way to phrase your complaint is to suggest that hardware vendors disclose how many USB controllers exist in practice. That I would consider fair (and it may even be done somewhere already).