A truly new and good 50 1.8 without the macro capability probably could have launched for about $300 (with a sale price of $250 or so), and actually would have been worth buying over an EF 50 STM + adapter.
I don't mean to sound unfriendly but I can't figure out a nicer way to word it :-D Is there a "truly new and good 50" for $300" from any other make that shows significantly better image quality for anything like the same size and budget? What I'm seeing is that 50's are basically either double-Gaussian designs like we've had for 70 years, whereby 6-8 elements are kind of symmetrically repeated in a front half and back half that kind of match each other, or, completely new-school designs that are surely produced by computer algos and look like nothing in particular (such as the Leica 50/2APO, Otus 50/1.4, and Canon RF50/1.2). The new-school designs are far, far sharper, but also 3-4x the size of the old-style designs.
I've had the EF 50/1.8 MkI (pro build), 50/1.0, 50/1.4, 50/1.2, the new RF 50/1.2, and this. The RF 1.2 is 10x sharper than the rest but too big to carry and too expensive to break if I drop my backpack, etc. The RF 1.8 still produces far better images, to my eye, than my iPhone 13Pro, and I think it does a better job than any of my EF's. Not much, perhaps, but does.
That leaves the amount of bokeh from f/1.8. Well, in film days, to shoot friends at a dinner I'd need 800-1600 film, 1/15 at f/1.4, and between camera shake and huge grain you couldn't quite tell that DOF was also robbing you of sharpness. Today, with the 50/1.8 reliably hand-holdable at 1/6 on the R5, and practically no noise even at 2500, and of course 45MP, the sharpness lost to DOF is a lot more glaring. I simply never find myself suffering from bad subject motion, camera shake, grain and so on. If they come out with a new 50/1.4 I'm not sure I'd buy it, unless it's far sharper, and if it is I'm sure it will be far bigger. If it's much bigger at all, even the size of the EF50/1.8 on adapter, I'd probably put it in my camera bag not my backpack.
Given how much shallower it is mounted on the camera, for me the RF is a huge win even if costs more. Mine was quite cheap though.
Photo from
https://snapshot.canon-asia.com/sg/article/eng/rf50mm-f18-stm-vs-ef50mm-f18-stm-6-key-comparisons