The deathknight class isn't innately easy to play. We start them at high level and require players to have some familiarity with World of Warcraft (in the form of a higher level character) before they can make one. It's not intended as a class for beginners. That said, while the best DK tank in the world can do some impressive things, we don't expect every player to perform at that level to be a good tank. While it might be challenging to execute perfectly, the rotation is also reasonably forgiving, especially for heroic dungeons and normal raids.
Why don't you hold the other two DK specs to the same standards? Their rotations have been specifically modified to remove "rune tunnel vision" and enhance quality of life and ease of use, while you're telling Blood that its OK that it has to eat nails for breakfast because it's a hero class.
Disease management was significantly simplified for Unholy and Frost, but not only was Blood left alone, it had it's one last hope (glyp of Disease) removed.
Frost just had its blood runes flat out removed. Unholy got a brand new strike in Cata to cover its rotational problem.
No other spec in this game has been told that its quality of life concerns were unimportant. I mean, just cite any class that's had rotational changes since Burning Crusade. Affliction locks had entire DoTs removed from it's rotation because of QoL.
The Blood tree has talents that make you WORSE at doing your job (Crimson Scourge vs Blade Barrier uptime), talents that you either removed from other classes (Bladed Armor vs that warrior one) or you said you were going to remove ("talent traps" like Blood Caked Blade that don't actually increase your DPS), and talents that actually manage to be detrimental in heroic raids (Blood Worms not being controllable and attacking Omnitron shields).
So either Blood is literally a heroic hero's hero class above every single other class and spec in the game, or we've been abandoned.
Daxx, I want to be able to have fun with this spec. I want to be able to lift my eyes off my Blood Shield Tracker and runes and be able to see how much mana my healers have. I want to be able to make decisions on the fly without pulling out a calculator and discovering that applying my classes defining mechanic (Disease debuffs) will actually increase my damage taken. I want this spec to be great (and also balanced!), but it feels like... You don't want it to be?