People CAN reach a certain standard, and perhaps they SHOULD want to. At the end of the day though, nobody has a right to upbraid someone for not upholding very high standards that are well beyond what is required lihalacha.
I think Rabbi Reisman, on one of his tapes said it best. He stated that (he didnt offer an opinion why) Bais Yaakovs simply dont teach tznius properly. Focusing on inches and hemlines is one thing. Truly explaining what Tznius really means, might make the difference in doing what halacha requires and striving to be like Kimchis (he didnt say the last sentcne, those are my words, trying to convey his idea).