A few thoughts on "Overengineered":
Were British tanks overengineered? Were French tanks overengineered?
It is probably as accurate as stories like, Soviet hordes of Riflemen and Cavalry charging tanks with sabers. Overengineered Pak 40s, I have read these too (the only overengineered equipment would be something like the Gewehr 41).
The myth of cost effective Soviet and American tanks is still stuck in peoples heads I see.
The number of produced tanks reflects the demands of the forces, the army force size and losses. Weapons are also cultural and are based on a nations surroundings. The Hittites knew Iron works while the Egyptians relied on Bronze, yet they had a lot of experience with Chariots, just to give an "ancient" example.
To understand war economy and procurement one cannot just look on the narrow field of tanks.
The more "subtleties" added and the higher the quality of your gear is, the higher the CEV and the lower your losses are going to be relative to your opponent during combat (except things like capture, abandonment and subsequent blow up etc.). The Soviets had a very high focus on tank production, they also had tremendously high losses, hence their output needed to be high. The "lifetime" of a tank during wartimes is going to be dictated by the enemy, this will also translate into production quality. Loss rates and chemical analyses are quality indicators.
In fact, the USSR selected the best materials for their armed forces including high investments in relation to their per capita GDP, that is typical for communist regimes and dictatorships, despite prevalent famines.
The cost of a T-34 was comparable to that of a late war Sherman type (around 50,000$), with the USSR having only 1/3 of the per capita GDP of the Unites States. The Soviets were an interesting case: They managed to field such a large army and arm their forces, producing gear on the run. It was of lower quality but they kept the stream alive and it was specialized for the EF, occassionally it did not suffice so this is one of the several reasons why the war dragged on for 4 years. The interesting thing here is that T-34s still used the very same unmodified/unimproved Christie Suspension when the combined UN forces encountered them in Korea, the Americans sold them decades before, while the British already relied on heavily modified installments. The strongest weapon of the Soviets was always ideology and not technological innovations.
Germany was producing gear out of cheap materials and including components made out of Bakelit, they possessed steel stamping procedures and methods the Soviets did not even have before 1950 (after "acquiring" them), just look at the amount of wood the Soviets were using in all of their weapons (AK to AKM, that is when the true mass production started).
Cheap, Stg 44s, MG42s and MP 40s are good examples: Condensed (simplistic) sophistication and principles produced under resource scarcity and scrutiny (quality control). Precondition? Highly industrialized countries with manufacturing traditions. Germany, the Netherlands, Denmark, Sweden, France, Belgium, Britain, Czech Republic etc. they all have high manufacturing standards. The US Army is producing licensed Minimi FN Herstal MG 249s and Beretta FS 92 for the USMC, procuring HK416 and 417 for their special forces and so on, they buy them for a reason. Europe and Japan had high manufacturing skills and standards, it was like that before and after the war (although Japan was still in the development phase, comparable to the south east asian pacific region today). It is a question of reliability.
A better question would be: "Is a MG-34 overengineered in comparison to a MG42?" Yes, to a certain extend (and from and economic standpoint it is) but it is not an overall better weapon. It sacrifices accuracy and lifetime for ROF and manufacturing costs. Everything has ad- and disadvantages.
To answer the OPs question: Prewar manufacturing is always going to be of higher quality. Look at the Soviet quality drops during the war (especially Uralmash factory output 42-44, Nizhny Tagil etc.) and on the other side a lack of alloys caused a quality drop in 44 for the Germans. AFVs are going to have a "rough finish" not because of "overengineering" problems but because of the hopeless situation their country is going to find themselves in (or perhaps because they were built by unskilled/forced labour).
Producing lower quality weapons would have hurt the German armed forces, producing far beyond necessary levels would have also hurt their economy and resource pool. In warfare you want to have a combination of both: Quantity armed with gear of sufficient quality.
So if we would apply everyone's logic the issue should be reformulated: The very reason why Germany was able to fight against such odds (a middle sized industrial country), was because it had solid engineering and a strong economy. Imagine a country of the size of Cuba inflicting five times the losses on the US, making it deep into the Oak Ridge facilities in under 4 months.