The game industry has little open source libraries because most games cannot profit off the library being open source. It doesn't increase the marketing reach of the game (it might make good PR for the studio, but the studio doesn't need good PR, it needs revenue from sales of their game!).

And the high-end libraries are worth money, so unless there's an altruist contributing the code, it's not going to get open sourced. Things like speedtree, low-latency video play back (within the engine, like bink vidoes), etc, are all commercial solutions to common problems in games development, and none of these would be given away for free if they could charge for it!