seems like mostly a cake and eat it too thing. i want to buy lenses that create low distortion images. in the film days, without digital lens correction i had to buy big / heavy and live with a lot of aberration (EF 17-40: i am talking about you). EF17-40 was pretty popular before the full frame digitals became available.
That pretty effectively makes the point that 'optical correction' can leave a lot to be desired.
once the corners are dark, the digital lens correction is essentially cropping in. (2 mm-ish in the above example)
That is not correct. It's not cropping, it's digitally correcting the barrel distortion. Light that would have filled the corners was bent further into the frame, the correction stretches it back to the corners. As an example, when comparing the RF 14-35/4 (black corners at 14mm), with correction in DxO the resulting image gives a FoV equivalent to ~13.5mm on the EF 11-24/4 (which is essentially distortion free at 13-14mm as it transitions from strong barrel distortion to milder pincushion distortion). It helps that the uncorrected RF 14-35/4 has a FoV of a bit wider than 13mm.
But, now designs are assuming digital lens correction from the jump, maybe choosing to exhibit easier to correct distortions and better control hard to correct distortions. I feel like my full frame is wasted but probably need to appreciate the size, weight, and cost savings present in the lenses. I have to say I am pretty happy with the picts from the RF 24-240. I havent owned the EF 28-300 but it looked big and heavy. BTW, I also liked the Tamron EF 28-300 as a travel lens, DLC helps it too.
I like the have the cake and eat it too design approach. The full frame is not being wasted, as stated above. The advantages of designing with digital corrections in mind are evident. One need only compare the size, weight and optical quality of the EF 11-24/4 to those of the RF 10-20/4, with the latter having similar optical quality (after digital correction of both lenses), but being wider, much smaller and lighter, and cheaper into the bargain. That's a big win, in my opinion (and in my photo bag – I bring the 10-20/4 along a lot more often than I brought the 11-24/4).
I also like the RF 24-240 as a travel lens. I did own the EF 28-300L, it was big and heavy and nothing to write home about optically, especially at the long end. The wider portion was similar to the EF 24-105/4L, the longer portion was not as good as the EF 70-300L, so I switched to the combination of those two lenses and sold the EF 28-300L.