They say it's because of the pagan origins of the holidays. However, if you look closely, you will see that they don't mind the pagan origins of wedding rituals/ceremonies. So a more pointed question might be "why the discrepancy between which pagan practices JWs will endorse?" If they were honest, their leaders would admit that the real reason they demonize various holidays is to minimize distractions from towing the party line and lining it's collection boxes at the same time capitalizing on every opportunity to control. But they're dishonest, so they won't admit that. Besides, it's their job to make up dumbass rules like "thou shalt not honour thy mother when other human beings honour their mothers". That's what they're getting paid for. They're getting paid to spend their every waking moment convincing humanity that if only you disapprove of doing life however the other guy is, 'cause it's us against them ya know, then a guy on the fly in the sky will smile upon you, you, above all the others competing for his approval. HOPE is big biz these days. And nothings sacred anymore. Not even yo' momma. :O)