One of the issues with your plan to copy UT Austin is your insistence that the students with the highest weighted GPA are “higher academic achievers” and more deserving of admission to “top” UCs than other students.
Any non-holistic single measure of “high academic achievement” is going to result in a lot of gaming the system. For example, @Brissie reports the following problem in TX:
There are a lot of things that students can do to “artificially” increase weighted GPA that may actually decrease the genuine rigor and academic depth and breadth in their high school course schedule.
Holistic admission as practiced by the UCs may be unpredictable and imperfect, and frustrating for some students and families (particularly for those who feel that they “deserve” a spot at a “top” UC because of their GPA…)
However, when holistic admission works well, it can serve to:
- evaluate students within the context of their school and community
- allow students to take a variety of paths during high school instead of focusing primarily on min-maxed GPA optimization
- admit a diverse student body with a variety of interests and strengths
- select students that are a good match for a particular major or program based on their interests and preparation
Weighted GPA is definitely a factor in UC admissions, but it is less relevant at the high end when distinguishing between top students. For example, if you look at the UC Berkeley admission rates by weighted GPA, you will see rates start to plateau (and in some cases start to drop off) around weighted GPA 4.4-4.5: Admission and yield rates by college (L&S, CoE, CoC, CNE, CED) and HS GPA - #3 by LionsTigersAndBears
Why aren’t all the students with the highest weighted GPA being accepted? It is because a weighted GPA of 4.8-5.0 doesn’t necessarily mean that the student is academically stronger than a student with weighted GPA of 4.4. They may have achieved that high GPA number at the expense of other things.
Switching to a non-holistic X% admission system would be expected to encourage more “gaming the system” behavior (ugh!), and could also eliminate many genuinely high academic achievers from consideration at UCs that might be a great fit for them, because their achievement didn’t happen to contribute to a high weighted GPA number.