If I had to make a beginner book, I'd make it so that characters created with it were compatible with the full game, and yet more simple. A way to do this would be:
- Fighter, Wizard, Rogue, Cleric. Only. You can multiclass, though.
- Fighter doesn't get to choose extra feats. They are pre-chosen for him.
- Little-used spells get cut from the wizard list.
- Wizard doesn't get to choose new spells. They are pre-chosen for him.
- Cleric list is drastically reduced.
- Skills that see little use are removed, as are crafting skills.
- Combat options are reduced.
- If at all possible, make a single book that has all of the above, a bunch of monsters, a DM advice chapter, a (vastly reduced) magic item list, and a short adventure.