Normally, after generations of building up a myth by the church, people tend to not question the validity of FACT vs. FICTION. All one has to do is look to recorded history (the bible is anything but) and you'll see the great con of the church to try and stomp out those that didn't follow their heed. Time to wake up...It's 2014 folks.
The true reason for Christmas is the celebration of the birth of Christ. However, the Church calendar coincides with the timing of pagan holidays as the Church wanted to make it easier for early Christians to follow a familiar calendar with respect to celebrations. The Church also wanted to replace Pagan holidays with Christian ones.
The Winter Solstice was celebrated by most cultures and civilizations long before Christianity. With the coming of Christianity, the Winter Solstice was adapted in to a Christian celebration supposedly for the birth of Christ, although no one really knew or knows when this actually occurred. Most of the Winter Solstice traditions and celebrations were retained and continue to this day. What makes Christmas special for most people to this day is actually not the birth of Jesus, but the mid-Winter traditions of decorations, trees, gift giving, family, feasts, etc, all of which have pre-Christian origins.
Even though the winter solstice may serve as the pagan reason for the Christmas celebration, this is not the original significance of the holiday. Even though historical evidence proves that Christ was not born in the winter, Christmas is the time that His birth is celebrated. The season is meant to remind the world of Christ's mission to save humanity.
Everyone has a different reason why the celebrate or enjoy Christmas. There is no true reason for it. Some people enjoy being around friends and family, while others like to give gifts to love ones during that time of year. Christmas is holiday and doesn't need a definite reason for being here. We should just enjoy it.
No, I don't believe that the winter solstice is the true reason for Christmas. The season means something different to different people but I believe the two main reasons are to celebrate the birth Jesus for people who follow the Christian faith and to capitalize on the gift giving mood that the Holiday gives to people for the commercially minded.