This is not an invalid use-case. Not everybody wants to be 100% focused on productivity to the exclusion of absolutely everything else.
If you want to have something as simple as a background image, the only way you're going to be able to see it when using a tiling window manager is with gaps or transparency. Small gaps is arguably less intrusive than transparency.
e.g. see: https://www.reddit.com/r/unixporn/
This is not an invalid use-case. Not everybody wants to be 100% focused on productivity to the exclusion of absolutely everything else.
If you want to have something as simple as a background image, the only way you're going to be able to see it when using a tiling window manager is with gaps or transparency. Small gaps is arguably less intrusive than transparency.