another Point i'd like to make is that with the realease of factions and greater capacity for trade, wars could soon start over trade routs. Personally I'd like The option of destroying a competitiors Marketplace, however as it stands in order to effectively do this i'd have to destroy most of said players city. It's not just the risk of loosing everything that is reigning in players desire to siege, it's also that many players woud feel bad about destroying someones capital.
If I was actually involved in a siege camp i'd only really find it fun if it was against an equal alliance, but also over one of their smaller settlments (nothing to feel bad about)
That's why I wanted my more coservative option. Fighting to set someones capital back about a month or fighting to save mine would be more fun to me as there is much less pain or guilt than fighting for total destruction.