According to multiple sources and even people from this board, the StuG was the most successful TD in the entire war.
If they wanted effective they'd make the StuG.
Yes, but that doesn't reflect on the vehicle. Its doctrine, quality of enemies faced (soviets blew chunks tactically from *insert date* - mid 1943, and Soviets were the primary enemy faced by the StuG III), the situation in which its deployed, quality of the crewmen, quality of materials used to make it, logistics, etc.
You can make a direct comparison very rarely, as so little directly reflects the actual combat capability of any forces.
I bet the Su-100 is not far behind. If these new Jagd tanks prove to be successful, I bet we'll see the Su-100 before long. Same goes for the StuG III (and hopefully the Panzer III as well).
2nd best gun of the war (unless you count APCR for the US 90mm, or APDS for the 17lber), but its still outpreformed by the KwK 43 by about 25%. The point is that we didn't start out with one of the best, we started out with "THE" best.
Personally, I considered this update to be a test run of true TD's.