While I agree with the OP that the Beginner Box is fine product, it seems he forgot that D&D offered a very similar product back in the early to mid 90s.
Dungeons & Dragons Game (New Simplified Version) | RPG Item | RPGGeek
My brother had that box. As a stand-alone product it was very good, just as the Pathfinder box seems to be.
However, it had a critical flaw:
The "Black Box" was officially, and for legal reasons, a part of the "Dungeons & Dragons" line. However, "Dungeons & Dragons" was essentially out of print by that point - everyone was playing Advanced
Dungeons & Dragons, and that was the game that TSR wanted new players to move on to. So, they had a starter product that led in to a near-defunct game, and that they also
wanted to use as a starter product for a similar but slightly different
Which was really tragic - they had a great product, but it was killed by the shambles that TSR had made of things. The Pathfinder box, thankfully, doesn't share this particular weakness.