Robsp - 10:28 am on May 21, 2004 (gmt 0)

The optimizer makes a lot of sense for Google as it brings the average CTR per adgroup and hence the clicks to the highest possible level.

For G this simply means more revenue (which is why the option is default on). It is a very usefull feature when you are looking for traffic or want to test different ad texts on CTR. When you look for better ROI (like us) better switch the option off.