If a publication requests 1,000 word articles, isn't writing 2,000 words even better?

Not  necessarily.  Being able to reflect a view or interpret an idea in a written communication sometimes, in fact most of the time requires you to be concise.  Especially if this is in the context of a scientific communication, the writing must be concise and to point.  I think the less formal term is, 'use less waffle'!