It is truly difficult to determine which is worse, "modern" (say post 1900) Christmas music, or traditional Christmas music rendered by current performers.
It's clear that most post 1900 Christmas music is just flat out bad, and beyond that it often has nothing to do with Christmas. Just because it gets repeated again and again doesn't make it good. For example, Rudolph the Red Nosed Reindeer may be played in grocery stores across the continent this time of year, and you may have learned it in grade school, but that doesn't make it good.
Generally, the more recent the music is, the worse it is too. There are, of course, some exceptions. Perhaps Feliz Navidad, for example, is worthwhile.
But is this worse than old songs, sung by modern artists? Hard to say. The general approach most current artists have to Holiday music is to sing it about five times under speed and in a self indulgent manner. Stretching a vowel out over 15 bars, for example, doesn't make it good. Have a Hooooooollllllyyyyyyyy Joooooooolllllllllllllllyyyyyyyyyyyyyyyyyy, Christmas, for example, isn't really Christmasy.