Chromium still doesn't support SVG icons in browser extensions either. Not as extension's own icon or in the browser toolbar. Firefox has supported those for years. Chromium just scales the images to the nearest 16-dip.
Magic of course. Talking seriously, it's one more step you'll have to take care of when making extensions for multiple browsers. Using SVG's directly would be much more simple for the devs.
I thought you were suggesting chromium automatically scaled the SVG for the various sizes it needs. Are you saying you have to do it manually? That does sound like a nuisance.