ORIGINAL: timtom
Another reason American tankers were saddled with the Sherman was US armoured doctrine. According to this, US tanks weren't supposed to fight enemy tanks. Hence there was no need to design and built a tank that could take on the mid/late-war generation of German tanks, or at least there was considerable systemic resistance to this.
In American thinking, the tank served two purposes: Exploitation and infantry support, and the Sherman sufficed in both roles. Engaging enemy armour was the role of the TD's. The armoured division was essensially viewed as the modern cavalry division, it's role to exploit breakthroughs punched by the Infantry. McNair, fx, cited El Alamein as the model operation with regards to the use of armour. This is also the reason the US armoured division was somewhat short on combat power compared with that of the Germans - on paper anyway.
That's almost exactly what I was going to say. The U.S. designed the Sherman as an infantry component, and planned to use TDs (Tank Destroyers) to take on enemy armor. I don't know how often the ground pounders were actually able to implement that plan (probably not too often I would guess), but that's what the plan was.
[Edit: My apologies for helping continue the hijack...]
