While I understand the theory here, I think that this design philosophy is flawed. Following this theory means that divine casters have significantly more power creep than arcane casters. It's one of the underlying causes of the CoDzilla; divine casters get new spells as soon as a new book comes out, but Wizards have to pay for them, and Sorcerers might even have to die to get access to new spells.
Generally speaking, the type of game I've played with has had minimalistic use of splatbooks, so this isn't an issue. However, I've also seen powergaming players who abuse this. IMO, making a character research a divine spell would be an excellent house rule to tone down powercreep for players who want a more exotic spell list.