Sundering Spell: A bit much?

According to the Sundering spell description, a spellcaster with a Bearing of 13 could practically destroy the *entire* tower of Cirith Ungol from almost 70 feet away (range 5' per point of Bearing, 10 points of damage per point of Bearing). All that for only a Stamina test of 15. If it was that easy, you'd think that someone would have done it by now! lol

I suppose the reasoning for this is Gandalf's sundering of Durin's Bridge, but according to those rules someone with a Bearing of only 2 could do that.

Does anyone else find this a little excessive?

Unless I find a compelling reason for that spell doing so much damage to structures, I am going to rule it down to 5 points per point of Bearing at range, and 6 pts. per at a distance. Sundering bridges and knocking holes in walls is ok, but I don't want the characters in my campaign to be able to snap their fingers and reduce entire fortresses to rubble and bearly breaking a sweat to do it.