I know what you are talking about although my example would be starcraft 2 (oh yeah bought this one too).

I played on Hard and it was mostly a pleasant walk in the park (mildly to moderately
challenging at some points). Then on some maps (1 out of 10) I got my ass handed to
me, repeatedly. So I had to lower difficulty to normal on which case the map became
mind-numbingly easy! (and that coming from a Company that fine-tunes their game's balance to death).

Now perhaps there was some obvious strategy that I somehow missed (Or perhaps I am getting dumber as I age ) But the difference from normal to hard was jarring
(and also speaks perhaps of suboptimal overall balance inside the same setting).

Anyway I was speaking of a general trend I believe I am seeing (although in an
admittedly limited sample) perhaps "forced" upon developers by Market analysis etc.