There is always cleaning.
Trying to brown your engrave like a chicken with just the right laser settings is somewhat like using a rocket engine as a barbecue, It can be quick but making each pixel a different color by cooking each wood cell to the perfect brown without burning is asking a lot. Add in adjustments for the time of year the cell was created and you would be really pushing it.
With dot dithering every dot is the same depth and color, and different shades are made by concentrating the dots or spreading them out much like a newspaper photo that is done the same way having only black ink or white paper,
Much of the color you see after engraving or cutting is vaporized wood condensing back on the work or a quite ephemeral scorched surface or layer of charcoal easily washed away by many methods. I have even used bleach on occasion.