Astrology aside, are you suggesting that we only believe in things that we know for sure, or are tangible? As you said, we once thought we knew and now we realize that we didn't know. And the more knowledge we attain, the more humble we should be about how much knowledge we have yet to attain.
Specifically about astrology, I can't prove it right or wrong, so I simply observe - like I do with most things I don't understand. I am not quick to embrace magic potions, but I am also not quick to cast stones at something that I can make no sense of.