Why not?
Go is a game that thrives on evolution. Just like how 9x9 and 13x13 gave us fresh perspectives on tactics, I think playing with these sizes would open up even more dimensions to the game.
Plus, it’s just fun to think about the possibilities!
Ladder would be fun, and I know there’s been some work to enable more settings on ladders.
However, if it doesn’t get added soon, have you considered starting a tournament instead? It would demonstrate community interest at least oh wow i didnt realize it wasnt an option
Officially, via the interface, tournaments only support the typical board sizes (9x9, 13x13, and 19x19) that allow for ranked games.
However, there are hacks to make unusual board size tournaments happen (see the past tournaments of this group Leopard's Resting Tree, for example). I think that this may have been done by manually crafting a custom API call to site, while modifying the board size setting to something that is not official supported via the interface.
This suggestion, among other group-level ladder customization options, is on a ToDo list. Here is another forum post that mentions some of the corresponding GitHub issues that document these feature requests: