But my point here is: What features could I potentially have by not having video control take a chunk out of the available firmware? Your imagination is the limit here.
According to the Margic Lantern page http://magiclantern.wikia.com/wiki/7D_internals
one processor has 1.7MB of firmware and the other 5.1MB giving a total of 6.8MB. I doubt dual ARM processors share the same program area so it's likely they are at a minimum of 8MB each. I'm not sure NAND FLASH that small is even widely available any more, so more likely they have 16MB+ considering they cost well under $2 in moderate volumes.
Either way I'd expect the extra still features like extra bracketing would take well under 1K of additional code space, so really just a marketing thing plus not having too many confusing options in the lower-level cameras. It's easy to forget in today's PC world how small things can be, I just took a look at a Linux kernel + filesystem + application I built for an embedded system recently and it's 3.8MB, so it's a 100% given a Canon camera which no doubt would have plenty of RAM could run Linux.
Anyway not to move too far OT I don't think you miss any still features because of video, it's just what they want to put in there. Not that I'm arguing too much, I hardly ever user video either just treat it as a bonus that's there for no significant cost