What in the word usage adds scope to the site name English Language? The topic of language includes its own usage, doesn't it? And if the usage is redundant, is there a reason why we thought it helpful/necessary to emphasize that part of language in the name of the site?
I think, and kind of always thought, the meaning is:
"The English language (taken statically) and Usage (how it is used)"
There are not just usage questions. For example the etymology ones or "what does x mean?", I think.