I hear you.....it just hit me the wrong way at the wrong time. I also have a "foot in both camps" - - *grin* The other night I was gritting my teeth as a young lass who "became pagan" all of two months ago read me a lecture about how:"You stole the solstice celebration from MY faith...." etc.
Then I admit it was hard to keep from grinning as an older woman, who has decades of experience (raised roman, chose episcopalian early in life and Wicca for at least the past two decades) behind her, verbally slapped the younger down - something along the lines of "You are complaining about the theft of a holy day you have not ever celebrated in your lifetime, to a person who is celebrating as he has his entire life, by traditions far older then he is."
Oddly enough, both Christmas and Epiphany were celebrated under the old calender as well as the new, but the switch in present giving from Epiphany (Twelth Night) to Christmas occurred socially about the same time as the calender switch....
though several of my friends who grew up in the continental European community told me that when they were young, presents were still concentrated on Epiphany - and it is only within the last few decades that custom has switched over to present giving on Christmas....