I'll probably get my head bitten off for this, but I feel a need to speak my mind anyway.
I guess when I hear someone wish me "Happy Holidays," I take it to mean that they are wishing me well during the holiday season. I take it to mean they don't know me, nor do they know what faith I practice. They don't know whether I have a religious preference at all. Nevertheless, they want to wish me well, and they want to be inclusive of whatever belief system I practice whether it be the same as theirs or different.
If I'm with people I know to be Christians, I say "Merry Christmas." If I'm with people I know NOT to be Christians, I say "Happy Holidays." If I were with someone I knew to be Jewish (for example), and I knew that they knew I'm a Christian, it would seem strange to me if they were to wish me a "Happy Hannukah." I would far prefer that they say "Happy Holidays." And if they were to say "Merry Christmas" to me when I know they do not practice the Christian Christmas tradition, it would seem disingenuous--even strange. It might even seem like pandering.
Like it or not, there are many different faith traditions being practiced during November and December--all at the same time. When you say, "Jesus is the reason for the season," then I wonder what "season" you are referring to. Are you referring to the Hannukah season? Ramadan? Kwanzaa? Christmas? Jesus is definitely the reason for Christmas, but for the "season"? I think not. Unless you're referring to the gift-buying season associated with Christmas trees and Santa Claus (although I don't think either are mentioned in the Bible).
There are people of many different faiths from all over the world reading this board and reading this thread. To my fellow Christians, I wish them a Merry Christmas because that is how Christians address one another. If I want to address readers from different faiths so that I can include everyone, I could go on for a long time because there are so many ways of saying it. So, instead, I think I'll settle for the all inclusive, "Happy Holidays," and leave it at that. Then I know I've addressed everyone regardless of faith or nationality.
If you're offended by my "Happy Holidays" wish, all I can say is that no offense is intended. I'm simply wishing you well.