I don't mind Christmas lights at any time. I have now and then passed homes lit with Christmas lights in the summer! I think when it's outside of the normal Christmas season, it becomes a matter of personal celbration. I hate to compare it to something with less universal meaning, but what about those pink lawn flamingoes that some folks have in thier front yards. I don't care for them in my own yard, but I don't mind if someone else wants them. The only concern I would have is if someone's lights are shining in your windows because of the proximity and the angle.
We used to have a neighbor that grew something in his basement that required grow lights day and night for months at a time. Unfortunately, some of the light actually penetrated our blinds in our bedroom because of the angle and the brightness. That was somewhat inconvenient, but it reminded me of a summertime trip to Alaska, where it just didn't get dark at night. You just get used to it. But that would probably be more of an annoyance to some people than others.
As for the Christmas lights specifically, January 6th was Epiphany, and is the traditional end of the Christmas season, so they are late.