My point exactly. Minecraft is written so it is easy on the coder, but performs awfully. It should be optimized, so it is easy on the machine even if it means more work to the coder. A good idea alone is not enough, you cannot say, that todays raw processing power in enough to run a badly written game so why optimize? Just think about how much energy this game wastes if 1 million people plays it on a 500W desktop with 100% CPU (yes, that think green crap).
As for Daggerfall it was extremely well written considering the age it came out, and the resources it had to work with (yes I know it had some annoying bugs), even if it had to generate most of the places, Minecraft just does the same, no excuses here.