Stugs were produced in greater numbers then any German tank, even the Panzer IV.
If FH would really want to be 100 % accurate you would have to use Panzer IV and Stugs in nearly every map untill you are fed up with them. I actually hope they never do that.
Stug started out as an assualt gun, and evaluated into a tank killer going through many versions, so maybe 2 versions in FH is a little under-represented seen it's availability on nearly every battlefield and long time of production. But almost every ( German ) fighting vehicle had many versions, they ofcourse can't be all represented in FH.
I would also like them with a nice camouflage skin or netting instead of that dull grey skin that doesn't look that much diffrent form the DICE one.