I don't really like the feel of using these. I would much rather just tap two points draw a line and drag it where I want it. Why not use an entirely new design to make use of the technology?
When sketching concepts, line weight is created in various ways and used to bring a sketch to life, conveying information such as 3d depth, important areas, material strength, motion, mood, as well as the designer's particular style. I don't think this is intended for CAD and vector drawings.
Adobe said that the Line and Sketch apps are free (as well as photoshop mix), and in Line, there is a "soft ruler" you can use with any stylus or even your finger, minus the touch sensitivity of course.
Architectural drawings and design sketches such as dresses or electronics often have straight lines - but during creation process you just don't think that a side of something is "two dots connecting"