If you overfund it, congratulations, you can keep the cash in the 529 plans to help your grandkids.
College is becoming such a commodity that I would agree with public funding for the first two years / an AS degree. The problem of course is that the education requirements are a bit of a treadmill, with more and more required - and that funding education for "adults" (as much as 18-20 year-old kids are) is a little problematic. Much less problematic is funding school earlier, since it seems to show pretty clear benefits to have kids socializing and playing, and apparently this is something that requires expense. Go for it, I don't care.
On one hand, penalizing those who have invested to fund their own children's education is weird.
On the other hand, 529 programs are middle class pork anyways. There are a million different little ways to pay less in tax if you're "middle class" because we have decided that a million ways to prod, reward, and punish people for doing or not doing stuff with their money is better than a simple "this is what you earn, this is what you pay" tax strategy.
On the other other hand, adding more burdens to the pork system is not a good way to use nor dismantle it, it just becomes inconvenient for everyone.
On the plus side, the next two years will probably see a whole lot of nothing passed, except more pork for people passing the laws and more censorship, tracking, and less free internet, which thankfully everyone (except the people who aren't in office) agrees is of course necessary. Enjoy your 529s, they're not going anywhere.