There's been a bit of back and forth between FrDave of Blood of Prokopius and JB of B/X Blackrazor about the Thief and Ranger classes, as well as some discussions on Grognardling (especially this first one from blogmaster Staples on his Scoundrel class as a replacement for the Thief.) A big part of the debate is about whether the Thief and the Ranger are archetypes and thus true classes. FrDave and Staples say yes on the Thief (and Ranger, at least in FrDave's case;) JB amd I say no.
Now, I've come out before complaining about the classes, specifically saying that the Thief as presented is a profession, and the Ranger definitely is. I think the disagreement is because FrDave and Staples are defining "archetype" differently than I or, possibly JB, would. The key to what I'm thinking of is the way I contrast archetypes with professions. To me, a class isn't about skills and abilities or the trappings of a particular background. It's not about what you can do; it's about how you choose to do things and why.
This means that I don't think the existence of a fictional character with a specific skill-set means that that skill-set is an archetype. Bilbo Baggins does not make the Thief an archetype, nor does Aragorn make the Ranger an archetype. The key test, for me, is: can you use the same class in a different culture, with different trappings and a different profession? the Magic-User is just "the guy who knows the secrets of magic". The Fighter is just "the guy who fights things". The generic quality of the class names, often ridiculed, is the dead give-away. You could, before the proliferation of classes, have a Magic-User that was a robed scholar, or a half-naked shaman, or a merchant dabbler; you could have a Fighter who was an archer, a gladiator, a knight, or just a barkeep who got really good at bangin' the heads of rowdy patrons. How they do things did not originally define what they looked like, or where they got their money.
The Cleric is a little shakier, because there was a very early tendency to think of Clerics as priests. But if you think of the Cleric as the "holy" archetype rather than the "priest" profession, you can get the same kind of dissociation between the what the character does (for a living or a as a personal interest) and how the character does it. You can have a very devout nobleman or merchant who is not a member of a church hierarchy, but is still blessed enough to drive away evil and pray for the occasional miracle.
The Thief, as I've said before, is where the system starts to break down. There are definitely trickster archetypes in myth and literature, but the Thief is tied to skills specific to one profession. If you had a more generic class devoted to stealth, surprise, and alertness, you would have a true dissociation between the Trickster archetype and the character's profession, which might be "thief" or might be a snoopy son of a nobleman, or a bush scout, or a juggler, or many other combinations of cultural background and source of income.
The Ranger, then, is not an archetype, but is a combination of profession (hunter) with an archetype -- Fighter by default, but wouldn't Trickster work just as well? Or Cleric, for your holy hermit who becomes a wilderness survival expert as a side effect from removing himself from the temptations of civilization?
The key to me is to separate skills, which should belong to background, and special abilities, which can be gained later in ways described in the Four Monks or Clerical Vows posts, from the focus and gimmick of an archetype. The Trickster shouldn't be tied to thievery, because what's important is not the character's dishonesty, but the indirect physical approach to solving problems, as opposed to the direct physical approach of the Fighter or the direct metaphysical approach of the Magic-User.
Part of the reason why I did the Clerics Without Spells post was to make them more archetypal. The Cleric with spells is just a variant Magic-User, which is OK, but a Cleric without spells changes from someone who uses a direct metaphysical approach like the Magic-User into someone who uses an indirect social approach, asking a higher power for aid. I have previously described a Charmer class, who uses a direct social approach, getting bonuses on reaction rolls. That's an archetype that has previously been overlooked in D&D, although it would work great as either the grizzled leader or the intriguing nobleman. So, I think there's room for more archetypal classes, but many of the classes we actually wind up with are mainly variations on existing classes that could easily fill the same roles.
I'll finish off by pointing out that I do like some of the specific solutions of FrDave and Staples (Grognardling) for what the Thief and Ranger should be. In particular, I think the Thief's abilities should be entirely shifted towards surprise and alertness; Move Silent, Hide in Shadows, and Pick Pocket don't work well as skills unique to one class, but can work as side effects of a surprise roll.