I can remember that in DOS1 it was quite possible to get 80-100% resistances to fire, ice, electricity, and earth simultaneously, simply by buffing your equipment with elemental essences (or rubies). Also a lot of stuff gave immunities to the CC conditions. So, you could basically ignore all surfaces and enemies that deal spell damage (except poison and tenebrium).
You are talking about late game of the first game. We are talking about the fact in DOS2 the armor gives this effect already in the early game. Already in Act 1 I hardly cared about surfaced and in late game if you have thousands of armor surface are probably even more irrelevant.
The popular opinion (at least in this forum) that the armor system sucks, seems completely wrong to me. Maybe that has to do with "The Anchoring Effect". I played the game before getting to this forum and I think it is awesome. In our group it leads to actually strategizing like asking our mage to focus an enemy with low magic armor. Maybe that is trivial, but I like it.
This just shows, that you can't compare those two games, because you have not played the first.
In the first you had to stratigize too. Mages were weak at body building and physical resistance and but high magic resistance and Willpower. And warriors were the opposite. But if you focused the same guy with a physical and a magical attacker, they did not get 30-70% more HP just because of that fact.
