Depends on the sprue real-estate they choose to work in - the Conquistadors and WWII Italians had a lot more breathing room than the Afghans or Boxers. Yes, head options, asbolutely, and I can absolutely find uses for android/cyborg/robot heads! But, given a choice between a half-sprue and something bigger, I'd rather see the extra sprue real-estate and a few extra weapons bits, too.
And, it seems that WA can get a lot of stuff onto an Afghan-style half-sprue. For example, those very Afghans had five bodies, ten or eleven heads, four sword-and-shield kits, four or five long rifles, and a couple spare rifles and swords. Given the amount of space that the spare rifles and swords, and the shelds use, that's not bad at all. For a modern set, handguns, machine pistols, and batons need not take up much room at all (if kept as just a hand holding the item rather than a whole arm), and the fact that SMGs take up less room than full-length rifles or swords do (while the same left arm can probably be reused for different SMG or pistol options!) A larger sprue with more real-estate to work in could onlly expand the weapon and head options that could be included (The Ooh-Rah full sprue made room for four head options for six guys, seven rifles, two SMGs, a flamethrower, a shotgun, two BFGs, a sniper rifle, a handgun, maybe 20 miscellaneous left(?) arms, and a couple other accessories including backpacks. That a LOT of stuff, generally heroic-scale and bulky stuff with a large footprint on the frame at that!)
That said, I also appreciate the concept behind the Accessory Sprue, even if Accessory Sprue I was a bit of an odd one: With 20/20 hindsight, it seems to me that the first Accessory Sprue might have been better conceived of as a Cyborg add-on: both left and right mechanical arms, robot/droid heads, and beam/partical weapons (including those one or two heavy plasma(?) guns that seem to typically be included in a Death Fields box, and seem to be very similar to each other across different factions (so that they could have easily been shared via Accessory Sprue, freeing up room in the main Death Fields kits for something else! Well, too late now, I guess, given that the future of the Accessory Sprue concept is uncertain. (Then again, it seems to have made a comeback for The Last War, in a much more interesting format, so maybe it's not been abandoned yet!) A lot of "wish list bits" I'd otherwise hope to see in a boxed set could easily be offloaded to a well-balanced accessory sprue that could then be combined with a hypothetical Tactical set or Ooh-Rah or anyone else that fits.
Now, I can't help thinking of that Wargame-in-a-Box challenge when thinking of what might go into a new: what sort of options might be included in a set like this to encourage a Wargame-in-a-Box setup? Those alternative head options - balaclavas, police-style helmets and face shields, and the likee - are an easy way of doing that, as would even just one different weapon option for each guy on the sprue, so that the same tactical bodies could be built with a choice of at least two weapon options, and at least three head options, for different factions.
In the end, I think one possible ideal set (IMHO) would be one that could supply enough head and weapon options to support (optionally) splitting the box into two factions, waragme-in-a-box style, with a set like this one benefiting from at the very minimum two different styles of heads for two different tactical factions. A half-sprue can easily do that much. As many weapon and other head options as can be squeezed onto the frames after that are icing on that cake, and the Ooh-Rah set shows that a full-sizes sprue has enough room for at least six guys with four complete head options!each, and more than enough room for up to two sets of five "uniform" weapon kits each (six MP5s and six random, for example, with room for additional one-off weapons and a few small accessory bits besides!)