Why cant Bethesda just step up to the plate and show us Deities in their full glory...why?
Because they don't exist. It's like asking to see the turkey you served at dinner last night: it's not there anymore, it's divided up amongst several different people, mixed with other stuff, and no longer recognizable.
Or, more appropriately, it's like if 2 people were each told half a story, and they each told their two children half of what they know, and so on and so forth down the generations, until everyone knows exactly one word of the story. You ask to hear the story, well it isn't there to hear, but if you gather up enough of the people who carry a word of the story you can maybe get a feeling for what it was about. Occasionally, you might meet a guy who guesses enough of what the story is to tell it: it's not necessarily what the story was originally, but if it's close enough so that people don't know the difference this new story can kind-of sort-of take the place of the old one.