Canon has already done research and listened to their customers who use the EF version and who are looking to use this on their current/future R bodies. Not having to use a adapter is good enough a reason for them. Canon doesn't care about people's opinion who have no intentions in buying expensive lenses like these. Even if Canon did make every single change for those people (besides dropping the price super low where they are practically giving it away), those dreamers would still not buy it.
I know what you mean, but that still should not stop us from criticizing marketing decisions. For example I would probably never by a Porsche, even if I had the money, but I will always say that I hate that fake motor sounds. They (and other automakers) have built secret loudspeakers into their cars that produce the motor sound some customers want. I will also criticize that some luxury apartments cost millions of dollars, but you can't open any windows there.
You say that not having to use an adapter is already good enough for some, but then I have to ask why people, who use their cameras for sports or bird photography and will never use a lens that profits from the shorter flange distance of the RF mount, are also forced to switch to the RF mount, as Canon pretty much abandons the EF mount. Those people probably already earn a 600mm EF lens and now they might learn that they have to switch to the RF version, because the EF version might explode, if you use it with an adapter. What advantage does a sports photographer really have from the RF mount? Wouldn't he prefer a mirrorless camera with an EF mount, which would allow him to keep all his long telephoto lenses? For me it feels like a kind of blackmail by Canon. They only give you all the advantages of a mirrorless camera like IBIS and the much better autofocus, if you switch to the RF mount. Of course that is their way to generate the most money, but it may not be in the interest of their loyal customers.