For reference, see the volume of the BooksOfMagic (originally by NeilGaiman, but I don't think it still is) where hell was populated by various of these...
Phew. You meant 'why they stopped making the books of magic' not why they stopped making Barney. All Praise.
Presumably [he meant] one has to wonder why Microsoft stopped making the above-linked incarnations of evil... --AlexChurchill