Indeed it would seem that a significant part of Mormon theology exists primarily in the minds of the members... the absence of a formal creed means that each generation must produce a new set of gospel expositors to restate and reinterpret the doctrines of Mormonism....”
Then HOW can it claim to still be the “one true Church on the face of the earth” if every generation changes doctrine to suit its needs?
Because for Mormons, it is not - and has never been - about doctrine per se. The entire LDS system is about claims to authority and succession. Doctrine (or more properly, the altering of it) is part-and-parcel of the long-term LDS experience. "New revelations" and changes to "official doctrines" are simply mechanisms used to test the membership, to see if they're continuously paying attention to/obeying the current authorities, not just the past ones. It's not about truth or doctrine in their system - it's about making sure your membership is current.