It's an interesting conundrum. It also has additional issues. A Breton can activate Dragonskin, which lasts for 20 minutes in real time based on Skyrim's timescale, meaning that if Bruoch turns on his racial power he suddenly doesn't get affected by magic for nearly a half hour.

Neither game properly establishes limitations. Perhaps for the sake of story we should probably use Skyrim's full absorption but cap it's chance of activating at 75% so that there's always the chance to be magic blasted regardless of skill.

If a portion of every spell is absorbed, then it runs into the issue of suddenly we're all having to figure what half or so of a lightning bolt is going to do to someone. Situations like that seem likely to bog things down.