On the one hand, Chaza"l were so makpid about triggers that they said a man should not even look at the "clothes" of a woman, even when they are not being worn. On the other hand, there are so many explicit Gemaros that talk about these things openly. Obviously Chaza"l understood that the power of the Torah would protect the person learning from hirurim.
Aderaba, Chaza"l were open with these things to show that a person needn't be celibate in order to be holy - like the Christians believe, but rather one needs to learn about these things in a
holy way and learn how to approach these matters from
a Torahdik standpoint.
I think I heard something to this effect once from a Shiur by R'Meyer Twerski over here:
www.torahweb.org/audioFrameset.html#audio=rtwe_091006 (I am not sure, but it's worth listening to anyway :-)