I think the thing is that it's always been both. The freedom to hack and modify has always been inextricably linked with the $0 license fee. If the early free/open licenses had allowed source access and modification but come with a license fee, or if early FOSS had cost nothing to use but disallowed modification, I don't think we'd have seen the success that we have. The two senses of "free" in "free software" are and always have been linked.