And yet, as Li Shenron said, those were by in large a waste of space.
Less so than the new monsters in those same books. Much less so than the Dragonspawn of Tiamat that took up so many pages in MM4.
By the time the MM4 and 5 came out people had years of experience creating new NPC/monsters with levels.
It would indeed have been better had those sample advanced builds been in MM1. 4e did that, and it was an improvement. Hopefully, 5e will take the same route, as we're advocating here.
Nonetheless, those builds were still very useful. While it was indeed the case that almost any DM could readily build those monsters by hand by that time, it was still a significant time-saver not to have to.
That is why I think Pathfinder released a great book with the NPC codex, which gave 20 examples for every class they have. 20, that is one NPC per level per class.
Such a book would indeed be good. But while we can be reasonably sure WotC will produce at least one Monster Manual for 5e, there is absolutely no guarantee that it will ever produce any specific supplement (that is, we can be reasonably sure there will be some supplements, but cannot be certain there will be an "NPC Codex", or "Draconomicon"... or even the previous no-brainers like "Monster Manual 2" or the splatbooks). It would not be unwise to ask the question "what should be in the Monster Manual if it were the
only monster book ever to be produced for the game?"
And, in that case, it is my contention that stats for 'bandits', 'cultists', 'knights' and similar subgroups of "human" should be included.
But that is something I haven't seen a solution for at all, especially with MM4+5. 4 and 5 were just a couple of humanoids with pregen blocks that were taking up space that could have been filled with cool NEW monsters. I know, new monsters in a new monster manual, quelle surprise.
By the time MM4 and MM5 came around, 3e had thousands of monsters out there, and hundreds of templates just in case those weren't enough. The game simply did not need any more new monsters. Worse, WotC were quite obviously scraping the bottom of the barrel - have you
seen the new monsters that actually did make it in to MM4 and MM5?
So where they could indeed have dropped the advanced humanoids in favour of more new monsters, they would have been new monsters on a par with the Dragonspawn of Tiamat. Or, worse, monsters that were
less good, since they would have been selected from those culled from the books for lack of space.