Actually they kind of do exactly what you are requesting already … they just don’t make them official or add a date like WP.
@awesomerobot made a wonderful theme Isabelle
Grogu by @meghna is just one of many of her recent themes.
All they have to do is choose one of their themes add a the year and a common title … Disco21, Disco22 etc. (sorry Grogu) make it owned by @ Discobot so it gets all the hassle. 
A January launch with fanfares 
and your feature request is fulfilled.
May the force be with you…
btw I ‘skinned’ a lot of Vb forums back in the day … lol but it was the gallery addon and the way you could place category sorted thumbnails throughout the forum that had the biggest visual effect and created a real impact - better sign up and better community.
Sorted by Recently added, Most Views, Highest rated or Random … vertical or horizontal (1-10) thumbnails in places where hooks for banners and for ads already exist.
Forums on Cars, boats, bikes, vans, dogs, cats, goats, tropical fish, gardening, hiking, biking, sailing, gadgets, tech, 38" monitors 
, food, recipe pics, fitness etc. … a few suggestions from a few niche areas that need a gallery as well as discourse in words.
Then you have sorted thumbnails uploaded by your users on your home page and in sorted categories to visually improve your forums appeal. It really does improve the look, sign-up, and engagement.
Unfortunately business forums with 
: probably don’t need one.
Or one would exist.
The user uploaded to ‘their’ gallery and selected categories. So user profiles had value and were visited.
Here I can’t even load a pic of my cat or grandkids to my profile … zero community.
I’ve been on here 6-7 years what do you know about me? (Occasionally ‘arsey’ is a given)