The 98-00 versions seem to be the focus of the head gasket issue. The later versions got it better. Because there were so many 2.5's with issues, they have become less abundant on the market and it has been easier to find good 2.2's to replace them. The 2.5 SOHC wasn't sold in the JDM, so that has exerted an addition restriction to the number of good used motors, too.
Here, we drive them over 200,000 miles, there, they see half that, then they are traded in. Their economic rebuilt point in their culture is much more restrictive, in part due to emissions, and also lifestyle.
Costing out a rebuild on a 2.5, if it needs extensive machine work beyond a valve grind and rebore, buying a clean used motor becomes the cheaper alternative. Most Americans don't put 300,000 miles on their cars because of it. They won't pay to install another $3,000 motor when the car is worth $2400. Installing a used $1,400 motor is often viewed as pouring money down a hole because it would be worth more than buying another. Often they get scrapped out at that point, just the same as a Japanese owner scrapping his with 75,000 on it because he's forced to do a rebuild under his laws.
Each situation is unique, the motor has to be torn down and assessed on it's own, the costs added up, and the potential options weighed in light of seeing the numbers side by side.