boiled downboiled down
"i shouldn't be punished for making a mistake"
"if I win a fight, I should win the game"
not sure, why after making otherwise good points, you have to fall back to such a stupid comment.
The way you describe quick walling and the effects of it I would completely agree with you, but I very rarely see it pan out in the game as dramatically as you describe it.
In the end quick walling is a reaction towards a breached wall, costing you more ressources and making your economy less efficient in most cases. It doesn't mean you negate damage that already has been done, it means that you react quickly to a situation, realizing the problem a few seconds ahead of time and minimizing the damage done to you.
Can it be slightly tweaked? Maybe, but I don't see it to be a problem in the current game.
One thing that i could think of, which doesn't necessarily will have too much of an impact on quick walls, but also makes castle drops a bit more risky is to actually account for damage taken when refunding cost after delete of a foundation. Not entirely sure about this, as i've never tested it, but as far as I understand you currently get a refund based on the construction percentage of the building, no matter the damage that has been dealt to it. I think it could be reasonable to reduce the refund by the damage done to the foundation. I.e. if a university is 10% constructed it should have 210 HP and refund 180 wood when deleted. If it got damaged and only has 105HP at 10% construction it should instead only refund half of the cost ergo 90 wood. This would make quick walling with big buildings a bit more costly, while largely uneffecting house walls and palisade walls and in addition would make castle drops something you need to be a bit more sure about, as deleting a slightly built foundation could result in the loss of a lot of ressources. On the other hand this would have a huge impact on the dynamics of tower rushes as well, where deliberate faking and deleting of foundations is an important part, and this new mechanic would make it very convoluted how much ressources you actually get back, so this might not be the best idea. Just thinking out loud here tbh.