Debian already provides images with non-free firmware: https://cdimage.debian.org/cdimage/unofficial/non-free/cd-in...
I use these when installing on laptops.
I use these when installing on laptops.
Yes the iwlwifi firmware in particular is shipped on the nonfree firmware CD image. But the firmware my other laptop isn't. With the stretch rc5 non-free image mounted:
$ dpkg -c firmware/firmware-iwlwifi_20161130-3_all.deb|grep -c ucode
46
But instead of providing the b43 firmware there's only a network installer to fetch it: $ ls firmware/*b43*
firmware/firmware-b43-installer_019-3_all.deb
firmware/firmware-b43legacy-installer_019-3_all.deb
Looking over the packages more closely now it seems only the b43 package[1] uses this approach (although there might be more firmware that's not included at all).The Debian project already ships that sort of script in the current non-free firmware CD, so clearly it's not a legal issue. What it doesn't ship is the ability to run that on another machine as part of preparing an ISO to install on a fresh machine that needs the proprietary firmware.