And why don't you think men want to work in teaching, nursery education, nursing, as health assistants, various parts of the creative industries or lunch time assistants?*
Why do you think there are still distinct differences that the average boy and girl plays with even when they are given free choice and no pressure to select the toys?
Some of it will be subconcious biases and prejudices (on both sides) but I've a feeling that that doesn't account for all of it. Gender differences seem to be prevalent throughout school despite all the affirmative action done there.
There are plenty of good women who work in STEM, and plenty of good men who work in teaching, nursing and other women dominated industries. Perhaps we should just be encouraging everybody to do the role that they want to do and making sure all barriers and biases are minimized without assuming the end result should be an even mix of genders (or any other characteristics) across all industries?
*Of course this is a generalisation and there are men there, much in the same way as parts of STEM fields are heavily dominated by women.