With the launch of 2.0, many cool assets were added to our arsenal, but there is a small problem—a lot of them are specific to Line/Shape tools. For example, there is no individual "dwarven thin wall" as an asset; it's part of the Line tool now. The same goes for various dwarven stairs, or cave walls, etc.
Sure, it's easier to make walls like this exclusively with lines and shape tools, but with individual assets it's so much easier to add variety and make them more unique and add custom shapes to them that would look otherwise clunky!
It also helps with 90° turns, where the Line tool breaks and it looks messy.