I do agree that less focus on ECs would be desirable. However, there is a ceiling effect on the SAT, and major grade inflation (and differences in high school standards), so purely academic admission couldn't work at present. I'm not even sure schools would want purely academic admissions - the student profile would look VERY different.
I wouldn't say that students have become dumber - but certainly more spoiled; more demanding of hand-holding and accommodations (to the extent that in some top schools, 10% of kids get time and a half or more on exams); more interested in As rather than deep understanding. Some schools are more supportive of this than others. Even amongst some of the very top schools, Deans will ask faculty to postpone a course deadline (announced at the beginning of the quarter) for a student who helped in organizing a party... . If you want a rigorous institution with serious, mostly academically oriented students for your kids, look carefully.