Mysterious Akavir is beyond cool. Turning it into just a piece of propaganda and the golden scaled immortal vampiric half-snakes into morons would be a very lame move.
In reality, just about every piece of text in Elder Scrolls is propaganda. It all depends on your bias though. Personally, I like to think that most of Mysterious Akavir is true, if not only for the reason that I want to see a giant tiger dragon in Elder Scrolls VI. And to answer the question before, yes, lore is wonderful.
As for Tosh Raka, if he really did mantle Akatosh or just made himself out to be like Akatosh to the cat-folk are two distinct things. If he actually mantled Akatosh, and I'm sorry for repeating the question, would that give him the powers of Akatosh. If so, was it not then Tosh Raka who ended the Oblivion Crisis?
Many questions, good discussion.
-Hexon