Yeah, you're right about the IQ of some lenses. I saw a few reviews between the 85mm F2 and 85mm F1.2 and the IQ seemed to be very close to each other. For the 600mm F11, I personally found the IQ is lower than the IQ of the RF 100-500mm, especially when you start cropping. I am eagerly waiting to test the RF 100-400mm because a lot of people are raving about it
But still, wouldn't the 24-105mm F4-7.1 be a good enough kit lense? If this one is smaller, the starting aperture narrower (and let's face it: 6.3 at 50mm as maximum aperture sounds very low) and cheaper, I figure it'll be less capable than the 24-105mm F4-7.1 and that doesn't seem to be intriguing.
Personally, for telephoto and macro work, where the subject is typically fairly central in the frame, I'd have no hesitation in using the budget RF lenses.
The 100-400mm is a huge bargain, super sharp, fast focusing, compact, light, has excellent IS, and focuses down to half life-size. I use it far more often than my 100-500mm, the latter being reserved for animal photography on safari, or bird photography from a hide, where I need a wider max aperture, and the extra size and weight aren't an inconvenience.
The 800/11 is also excellent and is my go-to lens for bird photography in the tropics, where the bright light means that I don't have to be worried about the limitations of an F11 lens.
I probably wouldn't get the 16mm, as it would be used exclusively for landscape work where I need the highest edge to edge sharpness and detail rendering. *When* I can afford it, I'll go for the 14-35mm L, but in the meantime the T/S-E 24mm and 24-105mm F4L serve me well enough.
A friend of mine has the 24-105mm F4-7.1 on his R6, and from what I've seen of his photographs, the sharpness is probably good enough for non-critical use and yes it makes an excellent kit lens for anyone on a tight budget.
I think the 24-50mm will be a retractable zoom, and that the limited zoom range and aperture are indicative of two things - firstly that it will be very small and light, and secondly that it will be very affordable. It's almost certainly intended as a bottom end kit lens for the bottom end RF bodies, and I think it will *only* be sold as part of a kit.