Some of my ideas to defeat HV's would be that one could not build ANYTHING within a 7x7 square around the idol (Tiles can still be plowed/paved), hampering HV design somewhat, although this first idea is weak. It may be cheap, but it might allow wall jumpers to get in.
Attackers shouldn't have to wall-jump to kill the perpetrators. Hearthvault designs are tiny and will only hamper some locations for one. Wall jump can still be prevented by dropping liftables such as cellar boulders to fill the interior of the vault.
The next idea is a bit better, and defeats small vaults: Attackers that can get within 50 squares of the idol can erect a special "Invader's Tunnel," a structure that acts like a crossroad that links up to any village idol within 50 squares, and demolishes structures inside if necessary to make the exit point. It would require materials like a minehole, but slightly less. It would require six continuous hours to build, though, and uses 50% weariness to travel each way.
This is going to destroy small villages and many village layout, aka a huge majority of the villages in the game. Even large villages isn't going to be happy with this change. Beside that, 50 tiles is a huge distant to have walls be useless.
The third option to beating vaults I have would be a siege item I'd call the "Roadblocker" (Name subject to change. May just call a "Siege Tower"). It would be a tower-like siege device that could be pushed in place outside a wall, and would have an AoE 50% larger than a beehive. It's function; it disables ALL teleportation in it's effect radius. Heart fires and crossroads would cease to work in the AoE. It would keep vault dwellers from porting out (They can still port in... Heh heh), but the flip side is you couldn't port out either while in the area of effect. Surround a vault and you could make a killer's vault their prison. However, it probably wouldn't screw over big legit cities too bad since villagers inside could flee to the city center and port from there.
Gates render this ineffective against hearthvaults and that is just only one way to counter against it. What about village idol? It is theoretically easy for some joker to go around the world and build blockers all over the world and paralyze teleportation to many people.