I personally feel more comfortable with the webtoon format compared to the more traditional webcomic/printed comic format.
I like the verticality of it, its comfortable to read from my smartphone.
Yes, some artist do leave plenty of white space in the gutter, but there are other creators that experiment more with it.
Honestly there are plenty of things that could be improved from the format, and it would be nice if creators did like the UI-UX designers that they check how the content would look on a smartphone/desktop before publishing to make sure that things are legible, but that might take too much time to do, and more knowledge in readability.