In some cases, a command line can be a faster way to interact with a software because you don't have to load up a large interface with 30 options to achieve a single result. You can just type in what you need really quick and bam-an outcome.
Good question. But I can't think of a single prominent Libre design tool that is command line...
rm -r /*
Mastery of the commandline, like mastery of language, offers real freedom.
Because dialog is sometimes best performed in writing.
Because Carpal Tunnel Syndrom is horrible.