Distributed propaganda leading to a call for global jihad appears to have been, at least in part, a major source of the Madrid bombings which caused the change in the Spanish government leading to a withdrawl of Spanish troops once the new government took power.
That and the UK bombings only works if you accept Sageman's thesis of open-source jihad. It runs up on the shoals of certain facts about the bombers, for instance that many of them were hardcore jihadis from before 9/11 with dedicated al-Qaeda links - i.e. they were not principally inspired by IO efforts.

Troop decreases in Iraq came about as a result of the change in government and efforts by the current PM to ameliorate the image of the UK as Bush's "lapdog".
Ignoring the fact that troop decreases were on the agenda before and would have occurred if Blair had continued in office, and was a function more of the rabid unpopularity of the war in Iraq than of any terrorist attack. The change in government was again due to intra-Labour Party politics and Iraq, not any AQ propaganda effort or some sort of bizarre attempt to curry Islamist sympathies.

Basically, take a look at how their IO campaign has raised fears globally as well as their destabilization efforts in a number of countries.
This is so generalized an argument as to be useless. How has their IO campaign "raised fears" in a way that led to a sustained price rise in oil? In what way has their IO campaign destabilized a major oil producing country? How much "risk premium" is built in specifically due to AQ's IO campaign, and how much has this affected world oil prices vs. things like a world-historical mass industrialization event such as has taken place in China over the past 15 years?