Well, Google has their handy little graphic set up for today, and I found a page entitled Mothers Day History ~ The Complete History of Mother's Day
Some relevant quotes from this:
Only recently dubbed “Mother's Day,” the highly traditional practice of honoring of Motherhood is rooted in antiquity, and past rites typically had strong symbolic and spiritual overtones; societies tended to celebrate Goddesses and symbols rather than actual Mothers. The personal, human touch to Mother’s Day is a relatively new phenomenon. The maternal objects of adoration ranged from mythological female deities to the Christian Church itself. Only in the past few centuries did celebrations of Motherhood develop a decidedly human focus.
Basically, there is a long tradition of celebrating mothers. Which seems natural given what we know of anthropology and human nature. The article goes on further to talk about the American origins and history of the holiday (which seems to be the main idea you are driving at):
The first North American Mother’s Day was conceptualized with Julia Ward Howe’s Mother’s Day Proclamation in 1870. Despite having penned The Battle Hymn of the Republic 12 years earlier, Howe had become so distraught by the death and carnage of the Civil War that she called on Mother’s to come together and protest what she saw as the futility of their Sons killing the Sons of other Mothers.
However, this didn't catch on:
Despite the decided failure of her holiday, Howe had nevertheless planted the seed that would blossom into what we know as Mother’s Day today. A West Virginia women’s group led by Anna Reeves Jarvis began to celebrate an adaptation of Howe’s holiday.
But, someone took up the call:
After Anna Reeves Jarvis died, her daughter Anna M. Jarvis campaigned for the creation of an official Mother’s Day in remembrance of her mother and in honor of peace. In 1908, Anna petitioned the superintendent of the church where her Mother had spent over 20 years teaching Sunday School. Her request was honored, and on May 10, 1908, the first official Mother's Day celebration took place at Andrew's Methodist Church in Grafton, West Virginia and a church in Philadelphia, Pennsylvania. The West Virginia event drew a congregation of 407 and Anna Jarvis arranged for white carnations—her Mother’s favorite flower—to adorn the patrons. Two carnations were given to every Mother in attendance.
She finally had some success with her holiday:
Anna Jarvis quit working and devoted herself full time to the creation of Mother's Day, endlessly petitioning state governments, business leaders, women groups, churches and other institutions and organizations. She finally convinced the World's Sunday School Association to back her, a key influence over state legislators and congress. In 1912 West Virginia became the first state to officially recognize Mother's Day, and in 1914 Woodrow Wilson signed it into national observance, declaring the second Sunday in May as Mother's Day.
The fight about commercialization seems to have come after the creation of the day.
And as the article states:
By the time of Anna M. Jarvis's death, over 40 countries observed the Mother’s Day. Here is the history of the spread of Mother's Day throughout the rest of the world:
And then goes to list dates and traditions for other countries.