Siege battle area too big

I would say that this is mostly a problem with how big cities starts to become in Middle Ages and latter, and how close there are to each other. This problem for me was mostly solved by playing with bigger territories, up to 60 tiles in bigger maps, that I could make thanks to mod. I think that devs should push bigger territories to fix many game problems as it's simple solution., but some additional fixes as excluding other cities tiles from battles if they occupy borders of battleground would be also nice. Maybe even that could create a situation where 3 cities close to each other make a big scale war over a city between, where one city is battleground and other just spam units to push them in to near battle.

So I invite to bump up this Idea:

ADD BIGGER TERRITORIES SIZES