A lot of interesting and essential things have been written here, but I would like to remind separately what people pathologically forget. This element, among other things (immersion, logic, lore, preparation,
etc.), had design
sense of progress: it
reduced need for increase in inflation of gear's characteristics. This is not just "and also this", this is very significant bonus/addition to entire system, and most importantly, this factor is absolutely universal (not temporary/completely liquidated/depreciated) - relevant and logical for any content/next patch/expansion. Perhaps "pure vanilla" approach was a little dry, but I suppose if manipulate whole system of characteristics in gear at the same time, rather than twitch its different parts separately, everything will turn out much smoother.
Many, especially magic classes, were alarmed by behavior of such element (resistance) in PvP and PvE, but earlier there was characteristic of spell penetration for PvE, and for PvP this characteristic could, if question was correctly posed, be devalued up to 95% by presence of cap of resilience, everything can be easy and simple, you just need to not contradict logic.
Separate spit at those speaking about "
very boring stats". These are
characteristics, this is their purpose (their purpose is to help with differentiation of roles, their priorities and organization of progress - that's all, no any transcendental far-fetched rubbish) and right to be such (when they became "interesting", system begun to crack at seams, and design was falling apart, this was said before any "
interesting systems" appeared and what happened after only proved veracity of
such censor), talents are more interesting still not enough to overweight class' distinctive stuff, class mechanics are even more interesting - in
that order and only that.