(My personal pet peeve is that Kodi still doesn't know how to minimize CPU consumption when one is doing nothing on the UI. It should just stop rendering. This means I have to turn Kodi off on my HTPC+server setup to stop it from pushing my CPU in a higher power consumption mode.)
My custom media center is basically just a glorified 10ft-UI file browser. Opens media files in mpv (with some extra GUI to download subtitles and select audio tracks), Wii games in Dolphin, runs shell scripts (I have ones launch Steam Link etc.)
I realize that this might be a case of "simplify by limiting use cases" but I made it for me so it's fine.