I know this isn't something that can be done soon, but maybe for an expansion or even sequel:

When a city (with walls) gets attacked, the usual tactical battle map spawns, with no obstacles at all. Ideally, a wall would have gates which themselves had hitpoints and created choke points for the attacker. this way, a group of archers would be a way more suitable defensive party than right now.

If you know age of wonders, that's the kind of tactical battles that where really interesting imo. With a few archers and spells you could hold off hordes of enemies, if used wisely. I've won battles against all odds and that was a really rewarding experience as it felt like every single one of my moves mattered. In elemental, it feels more like manually doing the same as autobattles are doing, with maybe the chance of saving a soldier or two more than otherwise.