How arrogant of Christians to force another belief system on others! It's the main cause of conflict since. Of course, the irony is that religion is superstition as there are no gods, and there are more than 1500 how so take your pick OR... Apply the brain you were born with!
For example the Knights Templar who were one of the most religiously motivated orders to recapture Jerusalem from Islamic forces they also had a massive political and monetary endeavor as well. They set up a banking system like the world had never seen and used this influence to help or hinder Knights Errant that were making their way to and from the Holy Land.
I definitely think that Crusade leaders desired power more than salvation. As sad as it sounds, I think that the Crusades were more about garnering power for the church and its leaders, than it was about spreading the hope of Christianity. I think that those in a position to benefit were more than willing to gain power.
Using a blanket statement to cover the whole of the Crusades, which went on for extremely long periods of time and were led at various times by many different people, is very misleading. There were those whose main goal was power through the conquering of the Holy Land, as well as taking the plunder from those whom they conquered along the way (look at the sacking of Christian cities in Asia Minor on the first Crusade). Don't forget, though, that this was the standard method of paying the expenses of engaging in war. Rudyard Kipling expressed this sentiment when speaking about soldiers of a much later time, but which was close in spirit:
Loot! Loot! Loot!
It's what makes the boys
Get up and Shoot!
To say that the hundreds of years of war fought over the holy land was caused by one motivation more than another fails to capture the complexities of religious beliefs, geo-political views, individual aspirations, etc. It would be like presuming that WWII was fought primarily for one reason, but each country involved had different reasons for stopping Nazi Germany or allying with it.