-Volkihar are M.I.A.. Reported to be the Skyrim brand of vampires in Oblivion, they're now suddenly missing entirely without clues as to why or how.
FACT: The only source on Volkihar vampires before skyrim is a book written by a vampire. Maybe you were foolish enough to believe a vampires word on the abilites of other vampires but some of us aren't. The source was never credible, just because its in a book doesn't mean its true.
-Redguards have gone from detesting magic in Oblivion with one NPC's entire personality type being that he was the token black guy for the mages guild, and he went out of his way to make it perfectly clear to us that redguard hate magic. Another Redguard necromancer found in the game had to flee Hammerfell because the people there wanted to kill him for practicing magic. Come Skyrim, Redguard utilize magic no problem. The argument again is "a lot of time has passed!!" yes, but Bethesda left behind zero literary tools to suggest such a change was coming. Hell, they pointed us in the OPPOSITE direction, saying they hated it. Now they use it and Nords hate magic....Very awkward transition.
We aren't in Hammerfell why should every Redguard be cliche? and rebalancing races is required everytime the system changes. If you paid attention the Redguards bonuses in magic are to Alteration and Destruction. The schools Trayvond liked he was a trainer in destruction and sold mainly alteration. Maybe you shold pay attention instead of

-Shadowscales. They're presented to us in Oblivion like this interesting new concept of Argonian culture, then next game Bethesda says "NEVERMIND THEY ALL DIED LOL." Like wtf?
The DB was basically wipped out and the enitre political structure of Black Marsh changed after the oblivion crisis. How would the shadowscale survive?
-The Vigil of Stendarr are just kinda....there. They do nothing. What's the point? Is this an idea that was never fully fleshed out?
They explain themselves quite well.