Basically this and I am personally insulted that you even thought we were using this to cheat, in fact I would even go as far to say that this thread title is outright slander.
Your entire OP is based on the fact that we knew it was a "bug" in the first place. We never launch nukes, so how could we know?
We literally just based it on the simple context of security through obscurity, hoping that you wouldn't notice you were hitting a younger city and the fact it always worked never crossed our minds that it could be a "bug". There was certainly no malicious intent behind it.
I can promise you as someone that has been playing this game for a long, long time that this "bug" for want of a better word, was used without knowledge that it actually prevented nukes from hitting the intended city.
If we had known, we would have rebuilt the same city over and over again (as you mention) - but this was never done. Look at our nations and you will see that infra was built in many of them as more and more were nuked. Had we known this, it wouldn't have been the case and we would all have simply kept rebuilding the same city - please give me examples of that otherwise as I would be interested to see them.
Whether you believe this or not is up to you, but it's the truth.