Here's another consideration. With the "safe harbor" of training bases closed/restricted, and the growing requirement for jihadi replacements, recruitment from out-of-theater sites becomes necessary. This means active recruitment efforts and coordinated movements of the jihadi must take place within and across hostile (or potentially hostile) territories. In short, because of our actions in Iraq and Afghanistan, their supply lines are stretched and more complex and therefore more vulnerable to observation, interdiction, and destruction (roll-up).

Belmont Club had a fascinating post on the size limits of underground organizations. I think they break down at anything more than about 75 people, because communication and discipline become too onerous. They really need places where they can exist in the open, if they are to organize anything substantial.

1) Except they are still operating in the open...in Pakistan, often with the support of the IIS, Pakistan's CIA.
And while the death rate while in training in Iraq is quite high for them, the ain't no better, faster way to make battlehardened Jihadists then in combat!

2) Does it ever occur to anyone that one reason the US Army Colonel last week said "We can't win militarily. Every time I kill one, three take his place" was because many are Iraqis who have concluded that you are right - all the Jihadists around the world are headed for Iraq. Where they kill hundreds of Iraqis weekly! And where a growing number of Iraqis are blaming us, for exactly the reason you cite: we are so determined to keep terrorists out of America, we've created another place for them to kill - Iraq!

By the way - unrelated, but since we've been losing soldiers at the rate of about 2.5 per day all year, if Rumsfeld is right and the war indeed lasts 12 years, we can expect to lose another 11,000 or so soldiers before the war ends. And since the VA quietly admitted (or tried to keep it quiet until GOP Senators went ballistic, calling the Bushies dishonest or incompetent) that they budgeted for about 25,000 returning wounded soldiers total, but have already crossed 100,000! And the fiscal year ain't over (the VA's medical budget is, they admit, about $1 billion short this year with 3 months to go, at least $2.5 billion short for next year), and the war may last 12 more years! At the current rate, that means about 1,600,000 wounded servicemen/women over the next 12 yrs!