How much to GRE Quant scores affect an application with a very high GPA?

My general point was that the percentile does have an impact on your application, mostly if someone with a similar overall profile is competing for the seat. It's much safer to be close to the class average. 90%ile is a safe place, and to a GRE aspirant who wants to apply to CMU, I'll definitely suggest that169 is a very safe score.
Though, I cannot disagree with your arguments either. Someone with an overall strong profile need not worry too much about the GRE score being in the 90th percentile.
It’s always “safe” to be closer to the class average. But it isn’t a deal breaker. Like @Qui-Gon said, the GRE quant is nothing close to the rigor and depth of undergraduate coursework. It’s just another stupid standardized test.
The top programs care less about the GRE than they care about your grades in subjects they’re interested in. The only program I’ve heard of select candidates with high GRE scores is Princeton . The “average” scores posted are just a reference. And it so happens that people with a strong quantitative background do well on the GRE.

The only time the quant score could be important is if you slightly lower grades in school and want to get noticed by the admissions committee. I don’t recommend taking the GRE lightly but even if you don’t get a 167 or higher,it’s not the end of the world. There are several things more important - internship and research experiences,projects,essays,etc.

I go to a top 5 program on QN. The only time they’ve asked a student to retake the GRE for a 90%ile score was AFTER they were admitted. It just shows what they think about it. Good grades,relevant work experience and a well rounded profile is sought more than a high GRE score.