Defensive buildings under construction should provide partial defensive power

It would increase the uncertainty of an attack if buildings under construction provided partial defensive power up until they are complete. The attacker cannot know how far along the construction is, so it adds a new element to the attack, and allows players to more effectively streamline base upgrades without completely decimating defense strength.

Defense could build by 20% with each fifth completed, or something as simple as 25% strength until half-built then 50% strength until complete.

Sorry if this has been suggested before, I looked through the list and didn't see it.

I disagree. If a defense is upgrading, it's out of commision. Let me put an example: Your car gets in a car crash. You have to take it to the garage to get it repaired. Can you use the car while it is being repaired? Even for a couple minutes? No. So how can you expect a defense to do the same? :)

This would reduce the strategy of considering the optimal time to upgrade, so I don't see this happening, sorry.

They do. They just don’t shoot anything. Weapons killers still preferentially target them.

Use them as defensive tanks and make sure they add to damage%. HP is lower but still accounts for something.