Very true, but that doesn't mean I can still wish they filled it. Sounds familiar - my path was 70-300 f/4.5-5.6 IS, 70-200 f/4L IS (+1.4x II), 400 f/5.6L, 300 f/2.8L IS II + 1.4xIII & 2xIII. I will say that the 400mm had me satisfied for many years.
Then again from Canon's point of view:
- I purchased the 100-400
- I purchased the 70-200/2.8 II + 2x III. The image quality + AF was close enough to the 100-400 to no longer justify carrying it.
- I still wasn't happy with the image quality + AF, so I bought the 400/5.6
- I still wanted something with IS and a bit more reach, so after some time I used the money I was saving for the 600/4 II and bought a 200-400/1.4x with the justification that it is far more flexible.
So in the end Canon got a lot more money out of me than if they had just introduced a 500/5.6 IS in the first place.
Lol....I passed on the 100-400 LIS, and went straight for a 400mm f5.6 L.
Then I took up a 70-200 f2.8 LIS II and 1.4x and 2x teles.
Then I sold the 400mm f5.6 L and picked up a 400mm f2.8 LIS.
Apart from the weight, I couldn't be happier!