As is very well known, women are not obligated in time bound positive mitzvos. As is also well know, there are three notable exceptions: Shabbos, Pesach, and Purim. As usual, just because things have a similar structure, it doesn't mean they have the same underlying reason(s). Women keep the once weekly mitzvos of Shabbos because the mitzvah of Shabbos was expressed in one edition of the עשרת הדיברות as "don't transgress" and in the other edition as "keep/guard/protect/do". We learn from the double expression that anyone who is obligated to not transgress -- all Jews, men and women -- is also obligated to keep/guard/protect/do -- all Jews, men and women. It is basically a technicality of the way the mitzvah was presented to us. The once annual mitzvos of the Pesach and Purim is because אף הן היו באותו הנס/they (f.) were also part of the miracle. Not a technicality in halacha, but a logical imperative. That being the case, one may ask why women have a differe...
This is a paraphrase of the pasuk in t'hillim 84:7 -- "mei'chayil el chayil" -- which means "from strength to strength". In this case, it is my thoughts and ideas to those who are strong enough to be interested :)