1

We have night color feature in many systems. We have some wallpaper plugins, like image of day. Why not allow to create time of year dependent plasma theme? Theme creator could define settings dependent on season or time of day or whatever. Another approach is to allow user to set different themes to be active on different season.

This isn't be a new idea, because OpenSUSE Grub uses this - on winter there's animated penguin on winter scenery in grub menu. Maybe Plasma5 should have similar feature?

I wonder if they just periodically change the theme that's used? It's definitely simpler and easier to just have someone manually push an update to switch themes every 3 months than to set up a system to do it automatically. Especially in the current ever-changing environment where the details of the automation are likely to change over the course of a calendar year.
(see also: https://xkcd.com/1319/, https://xkcd.com/1205/; granted that's applying to work saved for a single user, so you'd multiply the values by the number of users that would use the feature, but I'm doubtful if there would be sufficient benefit to justify the expense on this one)