Adding my voice to this. It would be an amazing tool for web work -- the vectorized images look far better than the very small jpeg images used in lazy loading today.
Similar functionality is already implemented in Boxy SVG editor [1]. There is also another more powerful "Primitivize" generator which has more options, e.g. you can choose whether the vectorized image should consist from triangles or rectangles.
[1] https://i.imgur.com/I8Fq1bM.gif