Hmmm. I admit, I don't think I've _yet_ razed a fortress, but I've considered it and come close, when someone else had mausoleums or watchtowers and I had ... something decent.
It would make more sense, imo, if the forts didn't come right back at 100% strength. Given the month between turns, the least someone should expect to see is a fort at 50% (for a 2 turn fort) when attacking. Then again - maybe it should require a commander to do the build command to rebuild a fort? I mean - it
may make some sense for them to be able to repair a fort when it was their territory to begin with - lots of peasants (or corpses) to do the work, but an invader that took it by storm should face some work.
I'm not sure this would diminish the lesser forts that much - 12 defense tends to stall an army just as well as 25 does. It might actually diminish the value of capturing high ranking fortifications, thus improving their value.
After all - right now, I could have ... mausoleums. But as soon as I storm a mountain citadel, or a fortified city, I get a
great fortress, in 100% condition, that I'm not going to give up ever if I can avoid it.
(This is actually the case in one of my MP games - I have watchtowers, I'm conquering castles and building my temples there. I am _so_ not building watchtowers until all his castles are gone!
)
This means that having a high end fortification can be a drawback - your enemies can build cheap forts, and conquer yours and get full benefits immediately. If it takes 5 turns to build a fort, that fort shouldn't be able to be at full strength overnight, imo.