> This is a $1,000 lens--definitely not a kit lens.
It is also definitely not an f/2.8 lens like all the other top lenses associated with this camera. I too have found it puzzling just like the parent did.
Lens speed is not the end-all be-all of photography. The 24-105L is significantly longer and has image stabilization. Sometimes the ability to handhold with a shutter speed 2-3 stops slower trumps the ability to increase the shutter speed 1 stop.
IS lenses are generally considered better for all-around photography, particularly for subjects which do not move like landscapes. Faster lenses give you more ability to stop the action of a moving subject and a shallower depth of field (given equivalent focal length).
The 24-105L is probably the most solid general-purpose lens for a full-frame in Canon's lineup, it's silly to disregard it just because they offer a bundle with full-frame bodies.
All you say is correct and I agree that lens speed is not the only element to consider. As you noted, it is a trade-off between different factors.
My main gripe with the 24-105L vs. the 24-70L (i.e. the lens that came second in that chart) is not just speed in itself, but the fact that the former has a zoom extension of more than 4X (my previous comment should have been more exhaustive).
As an old-style guy, I usually am uneasy with zoom ratios over 3X because I believe they are detrimental to quality. So when I have to trade between zoom extension vs. something else, I often go for the latter. The MTF charts for the 24-105 f/4 L [1] and the 24-70 f/2.8 L II [2] seem to confirm my gut feeling...
IS lenses are generally considered better for all-around photography, particularly for subjects which do not move like landscapes. Faster lenses give you more ability to stop the action of a moving subject and a shallower depth of field (given equivalent focal length).
The 24-105L is probably the most solid general-purpose lens for a full-frame in Canon's lineup, it's silly to disregard it just because they offer a bundle with full-frame bodies.