If you want to build a damage-dealer or healer focused character, you need to focus on magicka or stamina respectively. Go with medium or light armor depending on that choice, appropriate weapon types, etc. A hybrid build will never have the same damage or healing output as a pure magicka or stamina build because of how the stats and champion points work.
The only time a hybrid build is functional is with heavy armor tank characters, primarily because damage output is not usually a primary concern. The versatility that comes from having full access to both of your resource pools is more valuable for a non damage dealer, because now you arent limited to just stamina or magicka for the bulk of your abilities. A hybrid gains the ability to pull from both pools to use a variety of skills instead of just one or the other.
But again, that only really works if you dont care about damage or healing, so it only remains a functional option for tanky characters. I enjoy playing hybrids myself, because I've always been one to pick the jack-of-all-trades/master of none type classes in RPG's. I'm hoping the warden really fits into that theme well for me when morrowind releases, just as my druid was in WoW.