In fact, in most sieges, it's never a good idea to stay in your city. It's better to stay somewhere else like a chaos city, racial city, near a wilderness bank or in an other city/hamlet just to prevent being bind-camped. You leave an alt or a player in the city currently in danger just to scout around.
Anyway, this is not about economy or balance. It's about the strong feeling. One of my best and most memorable moment in DFO was rebuilding a city from the ground-up with my clan and finally, building the wonder which took us a very very long time to make. Once that's done and once the whole server is done building their city & hamlet, these moments are over. After a year or less, it will be impossible for a newb or a whole newb clan to get this type of feeling; the feeling of contributing for a clan to build a city from the ground-up.
Raids and watchtowers should be a big mats drain. We are also increasing durability losses and encouraging using crafted gear over monster drops. So economy wise, there are enough mats sinks.Yes, big clans could wait for small clans to build up a city before capturing, but the opposite is true as well. Victory deserves a reward on both sides.Remember that there is no longer any multi sieging protection, and that to capture a holding you need to destroy all watchtowers. After capture, to secure the area, a clan would need to rebuild the watchtower network around their new holding.It will serve the same purpose, and it will be even more expensive for larger clans trying to own multiple holdings.As we said, we'll try to find organic ways to encourage destruction of buildings, but we want to avoid artificial "destroy X% to win" or to automatically level a city.