The reason is direct manipulation. You're not thinking in terms of the DOM's static flow when trying to create a design. Instead you want a medium where you can quickly transfer the idea in your head to a tangible form and try out different layouts, typography, colors, and visuals.
But there still exist the problem of converting that design into code, and that is a wasteful exercise. You might have found Protoship UIPad, a tool I'm developing (in early alpha), useful there. It can convert Sketch designs into code - HTML/CSS and even React. Sketch has been incredible for that sort of stuff. It is a vector design tool and its design elements are fully expressible through CSS and SVG, unlike say Photoshop which is a raster tool.
> This claim is typically met with skepticism. Isn’t generated code unusable? Are the elements going to be absolutely positioned? Would the CSS classes be named correctly, and how reusable would they be?
https://medium.com/sketch-app-sources/code-generator-to-crea...
Of course you had to code everything by hand yourself - you didn't ask for code, you asked for design templates.
Any tool can be used incorrectly in bad hands. The problem of choosing to work with talented and competent designers is largely unrelated from the choice of tool.
This and the massive misunderstanding – where two parties agree to "templates", and one delivers mockups to the other who expects coded pages – tells me that Sketch is a subject in the story, but it isn't at fault.
Sketch users can be very knowledgeable designers and very good communicators. Sketch itself doesn't teach design, and it doesn't solve communication issues either.
I also requested a responsive design.
What I got was as useful as a PDF.
Sorry, just kvetching on Sketching.
I just felt it was a waste of time that some basic coding skills could have solved. ;)