Except that we're not just looking at half of the duration with double the effect. The bigger consideration is actually the CD. PAL CDs are *all* longer than their effective match for a WAR.
Any main tank worth its salt would also rather have an ability with a 5 second duration on a 45 sec CD as opposed to a 10 second duration with a 90 sec CD. People keep ignoring the fact that the WAR CDs come back *way* faster than the PAL ones.
Also, a CD is only useful insofar as it lets you survive the situation for which you need it. If it's overkill for the given situation, you're not getting anything appreciably useful out of it. The WAR CDs are enough to keep a WAR alive through the "oh shit" situations that the CDs are needed for, and they can be used for *more* of those situations throughout the course of a fight as well as be used more readily because you're not having to weigh against future need nearly as much. Yes, you'll take more damage while they're active, but survival is the thing that matters.
Once again, I'm not saying that the PAL CD suite is worse than the WAR CD suite. They are simply *different*. The PAL CD suite is high value, low use rate. The WAR CD suite is comparatively low value with high use rate. A WAR that knows how to leverage those CDs (especially by stacking CDs) can do wonders with them. It's all about knowing how to utilize the tools given to you rather than expecting the tools to behave in exactly the same way just because you want them to.