Musings On DDI
I fall (or fell while I still played 4e) into the latter camp. After buying book after book at $30-$40 a pop, another $10 a month seemed like highway robbery.
The thing is, if DDI is as useful as its fans tout, maybe WotC should look at it as more of a tool to bring in more customers rather than a raw revenue stream. They could look at F2P and freemium MMOs as an example.
Buying a PHB would give you a code that would give you access to the character builder for races/classes contained in the PHB as well as access to Dragon. Buying a DMG would give you access to the Adventure Builder Tools and Dungeon magazine. Buying additional titles would give online access to the materials covered in those books. Of course, you could just buy the appropriate codes to gain access to the material you wanted.
Dragon and Dungeon become even more useful for previews to entice customers to buy those new books. I'm sure someone with more business savvy in the field could come up with more ideas along this vein.