If you haven't seen a Counter-Strike game played competitively, this weekend a "Major" tournament is being played in Katowice[0]. It's well worth watching a match to get a glimpse of the mechanics. It might also be fun.
I'm playing a lot of CoH because it cuts all the base building ceremony down to minimum.
You can maintain this belief until today if you measure "minimality/essentiality" by size (in MB).
Most probably there are other games out there that are even more minimalistic but for sure they're less popular and less known. You could make a case for DF (although there is no MP) or even C&C1 (just ignore the balance issues).
I think the words you're looking for are "micromanagement" (if it's about dealing with more than one unit) and "mechanical skill" if it's about having twitch reaction times (for last hitting, landing spell-combos, etc.)
I play DotA on and off, and thi is the part that irritates me the most :x
Here's an illustration:
http://youtu.be/5e8HZqF3cyk?t=2m1s
I also like this quote by von Neumann:
"If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is."
I confess I do wonder what would be the equivalent 'go of RTS games', where the minimal, essential dynamics are captured without all the bling.