I'm not a firm believer of "Scientific Validity" as most science is sponsored by the ones looking for the results. My Grandmother used Tarotcads to read the future and she was 100% right everytime. However there was no proove she would be correct upfront.
Regarding the "putting in a box". You can't put the universe in a box.... People are the way they are. You simply can add certain types to certain boxes. Heck, I see myself as a unique individual but on any given day I can come across two or three guys wearing exact the same, having the same haircut and have the same attitude as me. It really is as it is.
Good points. Science only measures what it has tested and knows. But with something like astrology, even if there are guideposts based on something real and tangible, the practice also is open to an awful lot of opinion and guesswork. Some peoples' intuition is spot-on, though.