The Request for Bids document was written around a Sig. It might as well have said Sig only. I can see where modularity means something to the military. It doesn't mean squat to me.
Doesnt mean much to me yet. Since poly guns and now modularity are present and future, It would be nice to build a custom gun from parts at a non custom price. Pick a grip, slide, caliber, trigger assembly and leave the store with exactly what you want no mods needed. I think that future is probably pretty close.