Actually I am with you and I think like you.
But still, it is not easy to come up with a good idea of new content in the game. Just saying "others will do" is not content at all. It stays speculative.
What I say is, we, the community (I know, not all), don't present good ideas of new content. Thats not true in this strictness, but it is true in a general sense. We complain about lack of content, but there is not much content proposals here. Not much means very little.
Yes, I can easily produce ideas of new content, but I can not easily produce ideas of content which are realistic and possible to implement in a reasonable way of costs and effort and still bring good "content" into the game. And there is more: "content" is a very general word. Try to define what is ment by "content". I fail.
I kindly disagree with you, take New Vegas for example, many people thought "there's just so much you can do with this game in terms on content from mods" and guess what? people have made the game something Bethesda/Obsidian could only dream of