Isn't the control ring on RF lenses only? I could be wrong, but there isn't a control ring on the adapters. There does need, I think, to be some native non-L lenses precisely to take advantage of that feature ability and to make the RP/R series cameras more attractive to some. Those could churn into future customers for the high end lenses. Personally, I'd have never bought an "L" lens (or FF camera) had Canon not got me interested through the EF-S and non-L EF lines. My track was XSi, T5i, 70D, then 5D Mark III. Had 1 L with the T5i (EF 400mm f/5.6L), Then expanded that when I got the 70D (EF 24-70mm f/2.8L II, EF 70-200mm f/2.8L IS II) before I got the 5D Mark III. To me, a non-L line of RF lenses makes sense. There are still features one can only get through the native mount (control ring and improved AF capabilities, if I am not mistaken.). In that sense, adapting EF to RF is exactly like adapting 3rd party glass if it does not have the control ring or take full advantage of R/RF AF capabilities. Canon might think differently. We'll see. I suspect the majority of owners do not participate in forums.If Canon releases a hi-res body (60+mp) then it needs a set of lens that resolve to that level. No use releasing the body when the resolution can't be used.
What I don't understand is why there needs to be a new set of non-L lens for the R mount. There already exists a wide range of cheap EF-S and EF glass that can be adapted to the R or RP body. The emphasis from the reviewing community that cheap glass must be native is very strange to me... just weld on an adaptor and get even more with control ring or drop-in filter features. It is not like adapting 3rd party glass like Sony/Metabones/Canon for instance.