Yes, it's obvious they want to avoid a specifically Christmas image
It could be. I didn't see any Hanukkah ones either this year, come to think of it...
I doubt it, why would they do that?
Some Athiest probably complained and Google caved.
I'm just betting that everyone who complains here about Google's Christmas tribute is going to continue using Google search. Personally I thought it was way more creative than just a typical cliche Christmas tree and Reindeer logo.