I would certainly buy them. Also various native Americans especially Apache, Comanche and Kiowa; all nations that have been largely ignored. If Strelets covered the Mexican wars they could produce some very colourful characters; including Mexicans in sombreros and regular Mexican Army.
Even though such a set would fit better with my 1/32 needs I would appreciate a set or two in 1/72 scale. I've used the Prussian Landwehr as US troops of the 1850s in overcoats - you do what you have to do. By the same token, the shorter jackets of the US uniform could probably be used as another nation's troops with a little imagination. I'd have to research it.
It is a gap that hasn't been adequately filled. I didn't even bother with the Imex set - their Alamo Mexicans' and Saxons' and Vikings' plastic totally turned me off their product.