What's going on? Practicality.
When developers make a 2009 game, they strive for the best visuals as possible (unless not intended)
When publishers release a game, they strive to get the game to the most people playing (buying) their game as possible..
When CEOs want to release their game, and make the stockholders happy, they want to release it in the quickest way possible to make the most money..
Hence, they tell the engine developers to keep it simple
In different companies (eg ran by developers instead of CEOs) they do tend to care a lot more about technologies used and keeping it up to date..
Obviously visuals are the biggest selling point at this point -- however, they can accomplish that fine with DX9.
This is my 2 cents (from what I understand about the market anyway...)
Other things to consider:
- Games either succeed RIDICULOUSLY or fail immediately.. it's genuinely been like that for as long as I can remember..
- It may take a lot more budget to invest in or create an engine that supports DX10/DX11 rather than using what exists.. to no monetary benefit (people will buy the game anyway if it's good)