The visible result has been the weakening of these institutions. Do also observe that this is recursive — as these institutions have lowered their standards over decades, the people who go through them and end up leading them are weaker, too.
For one, why pay UC prices for remedial math? For two, community college has a lot more sections of remedial math and more experience teaching it.
If you're in a degree that doesn't need much math, taking remedial math at UC is probably fine; but all the STEM degrees want at least the full calculus series (afaik).
Eh, somewhat. They want some of those outliers hobnobbing with the legacies.