The more recent christmas songs are greed based wheras what I think of as a christmas carol is based on the birth of Jesus/pagan midwinter festival and written for faith not money
Definately some are produced primarily for commercial purposes. There are some modern Christmas Songs that are just really good; still written well and not just for commercialism, in my opinion. "Mary Did You Know", comes to mind. I have always liked "Little Drummer Boy" and it is fairly modern.
I'm not really sure where "Grandma Got Run Over By a Reindeer", fits into the equasion, however.
From a different perspective, however... Last night my 13 year old daughter played Christmas songs on her violin for 25-30 retired folks at a local Retirement Community and I was really touched. I could hear many of them singing ALL of the words very softly while she was playing and they were just genuinely happy to be singing them. Later they, as a group, just sang carols accapella. There is something magical about the old songs and the memories they bring.