I've stayed away from this debate so forgive me for not reading everything proceeding this. Nekros, you mention the evil dragon sent to destroy the world as bad writing. Don't you think the mythical similarities with Ragnarok is hugely fitting in a game like Skyrim, full of TES version of Norse symbolism and religion?
Over simplifying it as you have done ensures you miss out all the good bits: The hero, a soul of Akatosh and Shor the dead god must defeat the Dragon as he does every cycle in a land where the rain is the tears of his grieving widow, Kyne. The quest takes him through a sundered, kingless and bleeding land, ripped apart by a bloody civil war which culminates in an enantiomorphic event. The Pillars of Mundus are falling one by one, the Thalmor stretch forth their grim hand and humanity's fate looks uncertain.
I think Skyrim's Main Quest is pretty epic.
I actually like the Main Storyline, but I think they could do better. The Thieves Guild or the Dark Brotherhood questline is far more exciting than the Main Quest which makes no sense. I think the story and the background is great, it reminds me of the stories of my own faith, but the quests are a bit of a let down. It was supposed to be full of epic moments and stuff, but the only epic moments are when you first absorb the dragon's soul in Whiterun, when you do the same with the one at Kynesgrove and Delphin is like "So you really are..." and at Sovngarde which is the freaking Valhalla. Bethesda could have made it a bit more exciting, but I think they've done a great job with the storytelling of the questline.
Also, dragons.
I wish they involved the Dragoncult a bit more. Have Draugr lead by a Dragonpriest attack a few towns and cities, along with more dragon attacks in walled cities. Out of hundreds of hours of gameplay, I was attacked once in Windhelm.
Make me feel like the dragons returning are a more pressing threat instead of dragons circling overhead before flying off and the occasional fight. Dawnguard made the vampires feel like a growing threat with attacks on towns and vampire posse jumping on you along the road or in the wilderness.