So far, all week, everywhere I go people seem to be whining about how Skyrim is not as advanced graphically as other current blockbuster games, tends to have less performance and why it is still using DirectX9 rather than DirectX10 or 11. Most people I have talked to have been comparing Skyrim to other games such as Crysis 2, Battlefield 3 and mostly the Witcher 2 as comparisons to the grapical quality of Skyrim and the power of the Creation Engine.

First and foremost for those who keep comparing Skyrim to other games, Skyrim is a game that inhabits its own genre, yes it may be a high fantasy RPG but unlike every other RPG out there the Elder Scrolls series is played primarily in a first person perspective which puts it in the category of FPSRPG not just RPG. When it comes to graphical quality and design of the engine Skyrim and its predecessors, the designers have to take into consideration the ability of the player to interact with the environment, the fact the player can toggle between first-person and third-person on the fly and of the world's vast scale compared to others in its class. Unlike the Witcher 2 which everyone who is disappointed seems to be comparing Skyrim to; Skyrim is non-scripted open world sandbox gameplay where the Witcher 2 is scripted linear storyline gameplay, even though you can collect ingredients and make potions and stuff, the Witcher 2's game world is significantly smaller than those of The Elder Scrolls and scripted to the letter.

Why is Skyrim a resource hog?
Unlike the majority of games today and even role-playing games Skyrim as an extremely advanced AI that reacts to what is happening in the world and makes decisions based on numerous factors in order to make the experience unique for everyone. When it comes to other games many don't have unscripted random events, procedurally generated quests and a game world that is roughly 50 kilometers in size (based off how they said it was near in size to Oblivion) and contains no loading screens, this puts a great deal of strain on the engine and resources of the computer it is on. When Morrowind was released it was hard for current gen computers to run it, the same happened with Oblivion and the same is happening with Skyrim.

Why does Skyrim have low resolution textures compared to other games?
Many players are complaining about the size of the textures compared other games and go figure the Witcher 2 is on the list, one of the biggest reasons why Skyrim has lower resolution textures is because it runs DirectX9 and I will mention that later the other reason is the Creation engine which is still very similar to its predecessor GameBryo. The Witcher 2 (because everyone uses that as a comparison) loads and displays its textures much like the Unreal Engine 3 and idTech4 or 5 as you get closer the textures change and increase in resolution and textures outside of your field of view are kept at a lower resolution so if you can turn uberfast enough and your GPU isn't fast enough you will see the textures load, this is done by loading a small amount of the textures outside of your view before you see them so it can keep up with you turning all the time.
GameBryo and Creation use what is called a cell system where it loads a set number of squares around you aligned in a grid and loads every single part of those cells this way of loading is a resource hog but is efficient for how you can play Skyrim and how the engine can be utilized, with Elder Scrolls games you can zoom out very very far from your character in third person so the terrain needs to be loaded for this aspect, another reason is that Skyrim has a very high number of unique objects on the screen at one time than other games, you have to count every bandit if they are all wearing different armour, all of the collectable materials, distant LOD, there is buckets of stuff and very few games load so many individual items on the screen at any given time.

Why does Skyrim use DirectX9?
First and foremost Skyrim's engine is old, much older than the RED Engine with NetImmerse first being used way back in 2002 with Morrowind where is was on the edge of becoming GameBryo so you could say Morrowind's engine was NetImmerse/GameBryo. Even though the majority of the code since then has been rewritten by Bethesda it is still very hard to change the nature of the engine in such a grand scale, the other reason why they haven't upgraded Creation to a newer version of DirectX is because of consoles and Windows XP, many people still use XP and even more play consoles so it was much more of a strategic move by Bethesda to lave it as be than upgrade (with new consoles due next year or the year after we can expect the next engine to use DirectX10-11.1).
DirectX9 lacks advanced technology such a tessellation and texture streaming and threading and is limited in power, as I said earlier with new consoles, DirectX11.1 and Windows 8 coming we may see an upgrade for the next games or an upgrade for Skyrim in the future.

Also a quick clarification for those wondering why Skyrim uses XAudio2 instead of DirectSound: XAudio2 is DirectSound Microsoft just upgraded DirectSound and slapped a new label on it, so those who are complaining of sound issues and blaming XAudio2 because it isn't DirectSound, they are the same thing.
http://en.wikipedia.org/wiki/XAudio2

So I hope this answers some questions for those who bothered to read this, and no there isn't a tl;dr.