Offline/Maint Mode?

Will WordPress ever implement an offline/maintenance mode into the software? It doesn’t seem like it would be that hard, I never really took note of the numbers of different scripts I’ve used, but don’t ever remember having to search for the feature…it was just there. So common to me that it makes me kinda feel like WordPress is a relic…seems like such a ultra-basic feature not to have.

I don’t install wordpress into a sub-directory, so anyone visiting the site with the new install is instantly presented with development work…I don’t know, just wishing this basic ability was part of such “advanced” script…I know it’s been requested for years. Will it just never happen?