I think people get irate when their computer meets minimum specs, but then the game fails to run properly. ('Properly' meaning at decent framerates and decent levels of detail.)
The thing is though, that over and over it's been demonstrated in PC games that 'minimum spec' is not something to bank on.
If it's minimum spec, the game is going to run badly. Maybe with some tweaking it will run better, but it will never run well with the eye candy enabled.
You pays your monies and makes your choices.
The code isn't optimized that's true, but older rigs will struggle regardless and that's just life.