You have two ways to tell a consumer how someone looks. The visual and the cerebral way.
The visual is a (pun intended) no brainer. Look, aha, done. In a comic this means you take a look and you know how the character in general looks. Of course you can do a lot more funky things, show poses, costumes and so on, but the reader is not really imagining how that hero looks like. The reader knows. Same goes for TV and movies of course.
In the cerebral way, there is no longer a “right way” the character looks like. There is a description in text (or by audio) and that’s it. From that and the persons own visual memories, everyone crafts their own image. That might match in many cases, even with the authors image, but there are always a lot of differences.
This is why I like people drawing characters I created in a written story. What they draw is what I imagined, tried to describe on paper and then they re-imagined in their own head after reading those words. Such a result might be horrifying to witness as it often is completely not what the author has imagined, but that’s not really a bad thing. The reader makes the story their own by reading and imagining it, which is one of the best ways to know they like it because they actually enjoy the story enough to get creative with it.
And of course there is a time thing. I watched recently someone live stream how he paints with a tablet, from scratch. Watching paint dry is more amusing. In that same time I could write and edit an entire chapter with half a dozen new characters. This is not “writing is better than comics”, I have been doing both for a long while now, so I know what I’m talking about here and not taking sides. Just pointing out the discrepancy.
If you want the people to have an exact image, you need to go visual (comic, video). You pay for it with time of course (and other money costing things like equipment), while you can get faster (and cheaper) results by just writing.
