regarding the original post:
Well, I always thought like this: using days and months named after pagan Gods has nothing to do with worship.
the line of reasoning, at least the part, that was logical to me is like this: because of the command, not to mix true and false worsip, it seems consistent not to celebrate Christams and easter for example.
Why ? because both, Christmas and easter, have a clear religious touch in connection with Jesus Christ, while on the other hand are heavily influenced by pagan traditions, therefore original true worship seems to be contaminated over the centuries through pagan rites.
On the other hand, I never (even as full believer in WTS) understood the stance on birthdays, toasting, etc...
those things are not part of any worship, they are just traditions, like a wedding ring or a pinata, and even though having pagan roots (like almost anything today) it does not contamnje worship, because its outside any religious application today.
If the WTs would go this way, it would be more consistant, well, anyway it should be a conscience matter.
Above all, for none of this things there is a reason for disfellowshipping anyway...but thats another story.