Your logic clashes with the reality of facts being that this lens is going to replace the 24-105 as FF kit lens. And I can see why people react with a loud WTF.
Can I ask...what is the basis for your statement of 'fact' that the 24-105/4L IS will be replaced by the 24-70/4L IS as the FF kit lens, i.e. the 24-105L will be discontinued? Did I miss an announcement from Canon?
No, you didn't, but hopefully we can agree that everything points in that direction? The 5D2 wasn't discontinued the day the 5D3 became available, but we all knew it was going to happen. The 24-105 was due for a refresh, and the 24-70 is very much similar: standard L zoom, f/4, IS, etc. I also remember reading that it was going to be offered as a kit lens as well and I doubt there will be an overlapping.
Hopefully we can also agree that this new lens will not sell half as much as Canon would like as long as the more versatile, much cheaper 24-105 is around.