What I’d say is, I’m definitely in favour of keeping a 48px dock if we can also keep a 48px icon in Suru and add as many icons as possible to Suru (licence allowing).
I don’t think Ubuntu should ship a 48px launcher with a set of svg house icons that don’t scale well to 48px.
I also don’t think Ubuntu should end up with a scenario where only the house icons only are optimised for the default launcher size, if the house icons hardly cover any apps. Because then the majority of icons seen by the user on the launcher will be third party icons that don’t look good at 48px.
Also: if we optimise Suru full-size svgs to be sharp at 48px, we’ll have to tweak every full size svg to align it with a different grid, and they won’t be sharp when they scale to Gnome-preferred sizes of 32px and 64px.
I think I found the best way to show the problem as it applies to Ubunu. Here’s the full size SVG of the Suru messaging icon which, as per Suru guidelines, is drawn to a 4x4 grid:
The use of the grid means that the svg scales very sharply to 64px, 128px, 256px, 512px, because each grid square is a whole number of pixels at those sizes (1, 2, 4 and 8 respectively).
However, it isn’t optimised to be sharp at 48px. When the icon scales to 48px, this is how it will align with the individual pixels on your monitor:
A lot of the boundaries fall between the pixels so you will get a bit of blur there. Examples: the left and right edges of the squircle; the top of the speech bubble; the top and bottom of the lines on the speech bubble. Those lines will be blurry at 48px instead of sharp - EDIT like so:
Messaging actually doesn’t look too bad at 48px, but some svgs will scale worse than others. It’s just luck, how many lines and elements fall between pixels when you scale to a size that wasn’t intended or optimised.
Compare to how sharply the svg lines up with the pixels on your screen at 64px:
The new Gnome icons will be the same. I think it would be really weird to ship icons that aren’t optimised for the default launcher size and look better at other sizes. So: yes please to 48px launcher but then I think we need two svgs per icon (one following Gnome guidelines for larger sizes and another for the launcher).