I mostly agree with you.
About gamers wanting larger-than-life heroes who are safe from the woes of 'simulation', though...do you remember Dark Conspiracy? It was a game of 'horror' which sort of went out of its way to not kill the PCs, versus CoC which we all know about. It tanked, CoC still thrives. That's kind of an exception to the above, don't you think? Anyway, the whole thing is complex and multi-faceted. Most everything everyone has mentioned here no doubt had some impact on BRPs' relative obscurity. How much of each factor is very open to debate. Debate on, everyone.
It's fun.