Hi davem and Legate,
Points taken indeed, I especially liked 'simply made up stuff', which in a way sums up the entire Legendarium
I can imagine Tolkien making up a map feature on the spur of the moment then later weaving an intricate web of story and philology to explain its name and history. If we had been fortunate enough for him to live a thousand years I bet there would be few blank spaces!
Agreed on the lack of large settlements, I doubt there's an unmentioned Gondolin lurking in Minhiriath somehow! However I feel that there will be somebody around, even if just wandering elves, 'outsider' hobbits, Druedain, Rangers, Wild Men, Trolls etc. This is partly from the point of view that people always (on our world) move into new territory unless it is entirely inhospitable, and also from the books themselves. Whenever the protagonists move into a new area they meet new, and often unexpected inhabitants, eg. the three Trolls, Beorn, Tom Bombadil, Lothlorien (from Hobbits' point of view), Faramir, the Woses etc. Only the Trollshaws and Hollin appear properly deserted, the Brown lands are patrolled by orcs and even Midgewater has its midges (and, I strongly suspect, Mewlips). Many of these people are hidden away and therefore would not be shown on maps unless directly encountered by the mappers. (I guess you can tell I'm pro-Giant!)