Whilst I don’t want to argue about whether the appreciation of people in your life should be encouraged by a celebration day, I would like to point out that holidays aren’t specific to appreciating people . They can also be for appreciating things , such as natural phenomenon.

Personally I’d prefer winter and summer type celebrations on the equinox and solstice than Christmas and a seemingly random (in my country) public holiday at a point in the summer where it isn’t that warm anymore.