Never played morrowind enough to know if mod added monsters were a risk to the towns that were so open. How did that work?
All of the major cities in Morrowind had walls, but in some cases the walls weren't a perfect solution. In all cases though the walls were never tall enough to obscure your view of the sides of buildings and things as you approached. I can't comment on how mod added monsters affected things because I never added any mods that put dangerous stuff that close to a city. I don't think it's wise to do that in Oblivion either.
Honestly, it sounds like that Frost Titan was placed too close to the city to be safe. In a vanilla game, NPCs that go outside the cities can easily be killed and won't have the benefit of protection from other guards. So I suppose in that sense OC Bruma is actually more useful since the guards inside will gang rush anything coming near. But, that titan is likely to kill most of them off anyway, and if the player isn't paying particular attention the entire town could still conceivably be wiped out.
While we're on the topic of protecting the cities, is the idea of implementing archers patrolling the ramparts dead?
No, it's not, I've just been working on other stuff and allowing the current body of OC work to stabilize itself and work out remaining bugs.
Am I allowed to vote yes?
Sure, I voted yes too
What this revamp idea really needs is a new type of city wall meshes. Not too high, but not so small as to be easily jumped over on the run. Frankly, something like the wall heights in Morrowind. If they fit the general shapes of the existing wall meshes, that would be even better.