Q. We need to put 'Christ' back in CHRISTmas!
A. That is not a question. How about putting 'mass' back in while you are at it? In Old English it was Cristes Maesse. In Middle English it was Christemasse and that eventually got shortened to Christmas. So literally, the name comes from Christ's Mass.

Q. And isn't it terrible that people use that generic greeting, happy holidays?
A. Well, Christmas is a holy day so I suppose it's not incorrect to say that. The Old English is haligdæg. This is an example of why etymology cannot always be trusted for word definitions. Religious pluralism is difficult to handle if you are used to homogeneity.

Q. How come I never hear about Christmas in a Jane Austen novel or other books from that period?
A. That is a really good question. Maybe Michaelmas got all the attention back then?

Q. Has celebrating Jesus's birth always been important in Christianity?
A. No. Origen thought only wicked people celebrated birthdays. At least he cited that all the biblical examples aren't too great - just ask John the Baptist. I really wouldn't recommend Origen's hermeneutical approach here though. Anyway, there is no evidence of a commemoration until the fourth century. The Puritans even banned Christmas for awhile. In many cultures (especially in the Christian East), Christmas is a minor event compared to the Epiphany. In the United States, it is the number one event, overshadowing even Easter...but that is because retailers figured out in the 19th century that they could make a lot of money off Christmas.

Q. I like receiving gifts!
A. Doesn't everyone...the history of gift giving at Christmas time is a varied one. Different cultures give it differing priorities, exchange the gifts at different times or give them to different groups of people (children versus adults for example). Gift giving was not important in the early history of the United States, especially in New England given its Puritan background. From my reading, it does not appear like it was that important in England either (Christmas is for wassailing!). The different waves of immigration from various parts of Europe influenced the celebration of Christmas in the US. More than anything, though, it was the industrial revolution and the creation of a middle class. People now had money to spend on luxuries. They were reading (idealized) stories of how other people celebrated Christmas. The gift giving date moved away from the twelfth day of Christmas or New Year's Eve to Christmas Day. No longer were handmade gifts acceptable. The retailers figured out what they could do with Christmas and by the late 1800's and early 1900's you have a commercially driven holiday. If you want to read more, you could look here, here, or here.