My opinion on reserved days for celebration
Happy celebrations like Father's day/Mother's day/Valentine's day: All these days existed even before the card companies. There are plenty evidences to support the fact of origin of these days and people celebrating it back then. It is true that card companies did make such days known to more people and I am not complaining because these days bring happiness in celebration and gives everyone an oppurtunity to thank people (Mother/Father) who means a lot to us. We know we love them but we don't say it daily. So why not reserve a day to do that? Even a festival like Diwali is actually celebration of joy and those stories associated with such festivals finally end in celebration of happiness.
Women's day: I am of the idea that women doesn't need a day to celebrate womenhood. Card companies didn't make this one a hit but it was well thought by women's liberation groups and spread world wide for the cause of women. So again my opinion is that if we keep special days to each cause like oppression of women, Cancer day, AIDS, Smoking then people take notice to it instantly and such days do make impact on people to do more for the cause.
Source Wikipedia:
Mother's Day:
The first such Mother's Day was celebrated in Grafton, West Virginia, on May 10, 1908, in the Andrews Methodist Episcopal (now United Methodist) Church where the elder Ann Jarvis had taught Sunday School.
It's the US version of Mother's day that most of the countries celebrate.
Father's Day:
Father's Day is a primarily secular holiday inaugurated in the early 20th century to complement Mother's Day in celebrating fatherhood and parenting by males, and to honor and commemorate fathers and forefathers. Father's Day is celebrated on a variety of dates worldwide, and typically involves gift-giving to fathers and family-oriented activities.
Both of these have pretty recent origin IMO.