The problem with realsitic wall damaging is that it would need new models of broken walls of every type. Bonus points for broken towers, gatehouses, gates, etc. This means alot of work. The lowering is alot simpler and doesn't need new models, but also often leeds to glitches, floating objects and maybe easymode for attackers. I'd support a maximum lowering to half or so too, so maybe the smaller siege tower and ladders can then be used.