I see what you are saying, but I'm not sure if it will ultimately achieve what you are looking for.
Forcing the simulation of human error upon a human is rarely taken well. If you think that all the tanks should have their fastest reload times in-game to give some semblance of realism, I wouldn't argue with ya. However, I do think we'd see way more complaints than compliments if the system you're requesting were implemented, at least in that form.
You realize that currently, most of the tanks in AH are at or very near their "best" rate of fire, at least according to the printed sources I've found.
Also, I'm not insinuating that it is "human error" that is the issue, but rather the ability of the crew based on their expertise or training.
Assuming that all of the tanks in AH are at their best reload rate, here is an example of what I'm proposing: for the next tour, lets try to the T34/76 at 9 seconds, the M4x at 4.3 seconds, the Panzer 4 at 4.8 seconds, the Tiger at 7.2, Firefly at 7.8, the Panther at 7, the T34/85 at 7.2, etc, etc. Then the next tour bring them all down a half second, then the next tour maybe take half the tanks back to their best time and leave the other tanks at their slightly increase times. If the T34/76 were to have a stellar crew in it and be able to obtain a 7 second reload it might being a whole new dimension to the AH ground game, especially if the Panzer IV and M4x had slower reload times.