Studies after the war showed that the side that was able to get the positioning for the first good shot was the one likely to win the engagement. I know you are looking for a kind of Russians-were-oprationally-and-tactically-less-sophisticated-leading-to-greater-loss but soemtimes it really is as simple as the attacker will lose more unless the attack is operationally brilliant (by surprise, from behind, etc.)
Even overwhelming force isn't a guarantee of low losses or a fast breakthrough. The US infantry divisions in the Ardennes were green (102nd) or inexperienced (99th) and spread much too thinly, yet were able to delay, sometimes significantly, the "overwhelming" power of a Panzer army that outnumbered them greatly.
Likewise the British were not operational neophytes at Caen, and had the greater armor size, but they were going up against an organized defense. (Look up Operation Goodwood).
The army on defense generally knows the terrain better. More than that, they can use AT guns effectively, something the attacker can't. And they get to choose when enough is enough and bug out of there with as much intact equipment as possible.
While it is true losses where caused by always attacking, I do not agree that it is because of the "aggressiveness" in it self. But rather the lack of proper recon, proper support, coordination, composition of forces and logistical supply during advances by tank forces that caused the losses.
... I was under the impression that aggressiveness with tank forces are thought to yield less losses than caution of advance?
The so called 'Blitzkrieg' being the classical example of the idea.
....
So I don't disagree with you, I just believe that simply saying aggressiveness is an oversimplification that might give people the impression that aggressive use of armour is a poor choice.
(Well yes it is if you don't have recon, support, composition, logistics etc, )