Ummm I'm not sure if everyone is aware but WoW begins 5 years after Frozen Throne leaves off, so everything else is history and backstory, no more relevant than warcraft 1 to warcraft 2, or 2 to 3 and really yes there is a few holes, or things simply being rewritten to better fit, but the main plot is quite solid, especially for those who took the time to watch the teaser movie to Black Temple where it shows Illidan sealing the portals to keep the legion largely out outlands.
Also the actual difference in High and blood elves is that Blood elves fed off of demonic energy which is why their eyes turned green. Also many elves remained behind in Silvermoon to reclaim their ancesteral home and 'before Sunwell' await Kael's signal for them all to move to Outlands when it was relatively safe (Wowwiki.com is a wonderful resource)
Thirdly in my nerdrage, Arthas vs Illidan, we are talking Arthas, guy empowered by a creation of Kil'Jaden Sargeras' third man, he wasn't the lich king yet vs Illidan, a guy empowered by Sargeras, then ate the most powerful of the Dreadlords and took his power, then ate the power of the skull of Gul'dan and he is 10,000+ years old. It's a mircale Arthas beat him at all, killing him would have been really really tough
Forthly, comparing Deathwing to the balrog is like comparing A mon calamari cruiser to a stormtrooper, yes they have very very vague similarities, but in concept and essence they are completely different Deathwing is the Dragon Aspect of Earth and the burning inside of him is lava not fire, the balrog is some random fire demon with as much backstory as a new pair of pants.
Lastly come my age old question, if you have no interest in WoW why bother giving your opinion about how much you hate it? If you hate it don't read topics about it *Sighs* That was my nerdrage, thank you for reading