...I kinda go with what I heard Syl Arena say, that he only uses ETTL when the distance between the lens and the subject are moving....
With all due respect to Syl Arena, Joe McNally, Strobist and all the other advocates of manual flash, they have thousands upon thousands of hours of experience working with strobes and know them inside and out. While it's a good exercise to try to learn manual controls, to me it's a little like the original topic of this thread: if a tool is available that makes your life easier, why not use it?
If I live long enough, I may someday have enough experience to confidently set my speedlights on full manual. But, in the meantime, I figure I paid for Canon's top line strobes so I might as well take advantage of the technology they offer. As so many others have said about the original topic of this thread: it's about the results, not about how you got there.
Well, in controlled conditions, with manual, you seem to have IMHO, much more control of the look that you want...rather than the computer chip in the camera trying to tell you what you want.
Not saying it doesn't have its place, but when you have the time and control of the subject and environment, it seems to me at my new place on the photo experience totem pole, that you get more control of what you desire out of manual flashes, especially if you're shooting multiple ones..?
Just my opinion so far...