We don't use someone's idea of "best" purely based on their opinion. We make changes at a small level, we run studies, we actually find out what works, and stop futzing around with half-baked ideas of what will do what 20 years from now.
This is partly why I hate political discussions as-they-are-played... everyone has such strong opinions based on incredibly tenuous links to actual history, studies, etc.. Just "this is how it is, how it has always been, and if only I were in control I'd have this all tidied up right quick."
Of course I don't support alcohol prohibition. Haven't we tried that? Did it work? Also: we weren't talking about making smoking illegal, just about human psychology, and how people aren't logical. To actually give people better lives requires science, not "more laws" or "fewer laws".
I don't disagree with you on your other examples, generally, but I'll refrain from offering other examples that are obvious in the other direction... it doesn't get us very far.
"I don't vote for people so they can do my thinking for me" -- I half agree with this. I will gladly vote for someone who has thought and researched more deeply on important topics than I have, provided they can explain themselves and advance my own knowledge. In the end we are responsible as citizens for who we elect, so I do agree it's not much use to be snowed by anyone who uses big words or says they have the solutions.
For core principles, though... this is much trickier. Principles, in abstract, are useless. I agree totally with some of my older relatives' politics, when we talk only in terms of principles ("we need better education! critical thinking!"), but when we get into applying the principles we're miles apart.
"Free exercise of conscience", what does that mean in terms of specific issues? We should rely on lynch mobs instead of police? Citizen militias to take out unfair monopolies?
I'm in favor of encouraging responsible citizens who can think critically. I'm not at all convinced that your suggestions (inasmuch as I've seen them) would do that, based on what I know of human psychology.
I also have a suspicion that your idea of what social security payments will cover is a bit overblown. I don't have any living grandparents left, but my father is losing his house and has no medical insurance, in spite of social security.