I'm not sure if I'd be OK with destroying all buildings. It'd feel like cheating. From a roleplay perspective I can justify destroying buildings such as tier 2 forums and tier 2 mines that cause lots of squalor and public unrest by imagining it as an imperial requisition. The emperor saying "things are dire, find some rich landowners and confiscate everything - even the bricks of their buildings as catapult ammunition!" But destroying absolutely everything is a step too far for me. It feels like cheating.