...: simple rules, fast play, genre flexibility - is this not a GM's dream come true?...
It is. It strikes the fine balance between being coarse enough to be easy to run while fine enough to be engaging to play.
Similarly, I did a D&D Miniatures mini-campaign using the advancement rules from the Miniatures Handbook. It was fun, but I think the players felt there was not enough for them to do with their characters; which I interpreted as not enough player investment because there was not enough work for the players to do on character creation & advancement. Coarse enough for me to DM but not fine enough for the players (see above). The latest Gamma World had similar issues for us in play (see more above).
 
				 
 
		

 …OK……I’ll get my coat…..
…OK……I’ll get my coat…..
 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		