I found that when clicking the "Mod Menu" button, config screen for all mods that have config screens are created (ModsScreen#init). I don't think it necessary. It may waste times when entering mod menu screen.

It is necessary for the search bar filter for configurable mods. In English a search containing one of configurations configs configures configurable options only shows mods that have a config screen.
Some languages have translations for this, see the modmenu.searchTerms.configurable key in the language files.