And that is exactly the contention I have with this design. In tabletop RPGs, those DM-controlled characters are called Non Player Characters... the true definition of NPCs. They are not full fledged party members. It is fine for NPCs to join the adventuring party. But for the party to be solely comprised of one player character and the rest are the DM's (read developer, for the cRPG analogy)? That's ludicrous.
You're looking at it as the computer game taking on only the role of the DM, with the player taking on the role of all of the players. In games like PoE, Baldur's Gate, Ultima VII, etc, the computer takes on the role of the DM as well as that of the other players.
In tabletop RPGs, each player typically plays a single character. In small gaming groups, players sometimes play more than one character at a time, but it's generally pretty clear who that player's primary character is, and who are essentially the henchmen.
It is the equivalent of you and your gaming group going to the DM's home, and he invites you in but says the rest of your buddies have to leave. You'll be playing with his companions.
As a player in a tabletop RPG, you don't get to create or control the other players' characters either, so I fail to see any meaningful difference here. You can discuss with the other players to determine what the group will do, and you can interact with the NPCs to influence how the DM plays them, but both the NPCs and the other PCs have their own agendas and will frequently do something that you don't want them to do.
The Gold Box games, and others, got it right. Bioware got it wrong.
The model where you create a party of 4-6 characters on your own and make all the decisions for each one of them is not representative of the typical tabletop RPG experience. The model where you create and control single character and have characters created by someone else (and who won't always do what you want them to do) join you feels like a much closer approximation to the tabletop RPG experience, at least in my opinion. Without getting into multiplayer games, of course.
And of course, I'm looking at it from the perspective of one human player taking on the role of a single player from a tabletop RPG. From this perspective, games like Fallout, Knights of the Old Republic, Ultima VII, Arcanum, Baldur's Gate, etc, got it right.
If you're looking at it in terms of that one human player assuming the role of 4-6 players in a tabletop RPG, then yes, the Gold Box games, Wizardry, The Bard's Tale, Might & Magic, Icewind Dale, etc, got it right.
Both approaches are valid, and each one is probably better suited for certain styles of gameplay.