They probably feel there wouldn't be a significant enough market share and therefore dollars to make it worth their while to develop separate USB wired versions.

What would have been nice it to include mini or micro USB ports on the devices and allow them to work optionally via USB. It would probably take additional hardware (usb controller), more software (logic to switch between USB & BT) and of course supplying the USB cable. That would make for quite a unique solution on otherwise already unique products.

IMO, Apple doesn't tell people what's good for them. They have a knack for predicting what people will want. With some products at least. With others they simply watch trends and capitalize on them. When's the last time you looked down the keyboard and mouse isle of a computer shop? At least as far as Mice go, wireless seems to be very dominant around here. And I've only ever seen one mouse where you can optionally wire it up - it's from MS and it's otherwise somewhat of a POS in design (I have one).