I have always decorated my house, even though it's mainly for my own benefit, and even the Christmas after Ian died. (Although at that time it was also to give a sense of normality to the family). It gives a period of light at the darkest time of the year, and is thus very symbolic from my way of thinking. Obviously it can be a time when memories crowd in upon us, and we all have our own ways of dealing with them. (There is also that awful period just after the decoratiions have all been put away).
Perhaps bringing some evergreen into the house would be a more muted way of doing things, and making a special little area with a candle as a focus for thoughts, among the greenery. Also, some hazel or willow twigs in a vase...the warmth may encourage their buds to open, and that gives a hint that lighter days aren't SO far away. Nobody has laid down rules as to what we have to do as regards "trimming up" as they say in Yorkshire. For some people it is still far to early to be thinking about it, and traditionally, Christmas Eve is the time.
I agree, we should all bear VT in our thoughts. We forget among all thr glitz and merriment that this time of year can also be very dark for other, more subtle reasons.