I don’t get it either that the S lens is so long. But, it is optically outstanding and the same price (or it was) as a Nikon Z body with a 24-70 f4 when purchased as a kit.
Because the Nikon is using a modern, multi-element design with plenty of correction. It's better optically, but also expensive, heavy, large.
This new RF lens, to me, appears to be a simplistic double-gauss design. I'll take it a step further and say it even seems to be simply the EF 50 STM with lens groups shifted forward to make up for the flange distance with some (probable) slight projection tweaking and an additional element (maybe aspherical?) for improved sharpness wide open. Think about what the RF EF adapter is doing when you mount this lens, it's simply moving the elements forward. I think that's what this re-work is.
In other words, this new RF lens, to me, looks like a low-investment re-work of the 50 STM for mirrorless flange distance and RF mount, albeit with small changes to the lens formula to further enhance IQ (over the EF STM version)