I was just about to post about that subject. In my opinion, castle drops and the like (kreposts, TCs, although not towers) are by far the biggest problem of the game, and I keep wondering why nobody seems to be bothered by them.
The issue, I think, comes from the fact that in such a game military actions happen in real time (it takes a few seconds for a knight to kill a villager, for instance) but that building, for obvious reasons, happens at an extremely accelerated speed. Think of the time it took to build castles in the Middle Ages. If i’m not mistaken we are talking about years. That means villagers, to be conservative, build at least thousands of times faster than in real life. And the fact that your military units’ training is also sped up rarely helps you when dealing with a building drop. Building and the rest of the action therefore happen in two different space time realities, or whatever you want to call it. That gives the hammer of villagers a highly disproportionate effect compared with the sword of military units. Most players, maybe consciously but probably implicitly, have realized this and abuse of this discrepancy all the time, which makes for ridiculous games imo.
Now, building has to be sped up in such a game of course, but some mechanism has to be introduced to compensate. If I remember correctly, in older versions of the game unfinished buildings used to be very vulnerable, I don’t know why that changed. One way or another, vulnerability, or build times as you suggest, is a matter of degree and I don’t see why either could’nt be tweaked to reach the ideal gameplay balance. However, as the issue also extends to quick walling, I tend to prefer playing with the vulnerability aspect. An unfinished building can still act as protection for villagers. Right now building villagers can too easily finish a building that military units are attacking. 2 villagers can build a castle while 7 longswords are attacking it from the start. Moreover, in real life, destroying is easier than building. Imo, if 10 villagers start building a castle and 10 enemy villagers start attacking it 2 seconds later, it should be destroyed. That resistance could be increased as construction advances, so that the same 10 enemy villagers can’t do the same if the castle is already, say, 50% built. These numbers could be changed to reach the best balance.
The very names “quick walling” and castle “drop” are suspicious. Aoe is not meant to be a realistic game, but other unrealistic features usually have a gameplay justification for them, whereas castle drops have none.
I remember when I started to play Aoe2DE, seeing people trying to build aggressive castles and thinking, “What is he doing?.. He doesn’t have military control of the zone, I’m gonna destroy his castle…” But of course I quickly learned that’s not how it works. Ideally, doing a castle “drop” would be a risky business, and would have to involve careful planning, diversion or exploitation of military momentum and not merely abusing a game mechanic. It would make for much more interesting games, in my opinion.