Cognitive dissonance around the idea that there is room for improvement is inevitable.
And I'm surprised that I get the same blank stares from Americans that have lived for a decade in Europe. It's like they've never contemplated any other way of electing. Of course it's not true about everyone. I'm generalizing a lot here, but it still surprises me.
I also believe that "whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist." -- Lysander Spooner
No Treason should be required reading
The conspiracy theorist in me thinks it is because IRV doesn't effectively change things. The realist in me thinks it is just trendy.
For others: See me other comment (it is large, you can't miss it) explaining these topics in more detail (with links!)