I'm guessing that this is a case of being to chicken and trying to dodge major competing releases.
first it was trying to stay out of the gap between SWTOR and Diablo 3 (cause that was when Blizzact was gonna be ramping up D3's marketing, then it was finding the soft spot just after people started getting disillusioned about D3, but then they got negative responses durring TL2's beta and missed their window while working on things, now they are stuck waiting for GW2 to ship so that they aren't getting mashed up against that behemoth.
yeah, all of that are some pretty big hitters, but Runic really needs to grow some balls and trust in their product, Torchlight 2 is also a major hitter (providing they actually release it while people remember and care) and all of those products they are worrying about are MMOs, not co-op dungeon crawlers.
TL2 will be just fine, release the damned thing already.