Aside from being better prepared for standardized testing through more rigorous courses, I believe there is value in AP/IB classes.

Applicants need some way to set them apart from the general pool of applicants - That huge, homogenous group of kids with a 3.9 and a 29.

Extra-curriculars do that. So do the advanced courses. There is a reason there is a specific place to list them on the application. The more boxes you can check on the application the better off you are, even if it costs you a few tenths on your GPA.