They tried doing more comic art in a painterly/fully-shaded style (like the above) with Epic and Heavy Metal back in the 70's and 80's.  It didn't really catch on.

It was probably because it is far too labor intensive for a monthly, bi-monthly or even long-ish series of panels. 

Even with digital painting making this far far easier than it used to be, and the rise in prominence of The Colorist as a digital painter, it is still done with a relatively light touch in modern comics.

The gist is this:  is it IMPOSSIBLY hard to create consistent and appealing illumination from imagination panel after panel.  That's why CG was needed to unlocked that possibility.  When a human tries it, you get a very mixed bag that falls into that proverbial Uncanny Valley.

It works better for covers and such (low output), and requires lots of physical models etc.  like Alex Ross generally has to use.

Artists are forced to step back from photorealism at some level and make stylistic choices.  One of those choices is line-art versus painting (B&W vs. color too).

In the realm of line-art, graphite pencils allow a bit of wiggle room (compared to ink) that lets it teeter towards painterly techniques (smudging, levels of gray, etc.), but ink is the harshest of mediums---being essentially binary.  Each and every grey-tone is a decision point that requires a contemplation of how to fill/hatch it.  Like many, I have always held the layout-penciler as my hero, but have in recent years come to have equal respect for the inker (or disrespect, as the case might be --- looking at you Vince Colletta!).

There is an aesthetic to line-art that can push its beauty above that of painting (e.g. Gustave Dore's etchings, Franklin Booth's landscapes, Frazetta's Tarzan, or Wrightson's Frankenstein).  It is an abstraction of reality with its own harmony.  These days I find B&W line-art---with it's gorgeous contour hatching---far more appealing to my eye than painted pieces.  With the advent of cameras, CGI, Photoshop and the like, digital painting has devalued photorealism in art.  It's ubiquitous.  Too cheap and easy.  Conversely, I think it has elevated the skill-set necessary to produce great inked line-art because it is so rare and difficult.

This is an unlikely venue for appreciation of painted comics in the style of Iam's.  Most of us are here because we love a certain aesthetic---line-art and Mr. Byrne's line-choices.  When those are both obscured, our interest generally fades.

Like Mark, I agree that your traditional inking is much more impressive.  In truth, I am no longer impressed by digital painted "realism" across the board (amateur to pro).  It is so common now, and the bar is so low (what is hard in ink is easy in paint, and visa versa), it's become banal.

When Ross originally did it, it was at least relatively new to comics and executed at a very high, classically trained, skill level---be even he has recently tried reverting to line-art and flatter colors in his Fantastic Four: Full Circle.

@Eric:  Those are not bad.  Truly, I've seen far worse but...

a) I'd still I'd take Frazetta's B&W inks over those x1000. 

b) They fall into the uncanny valley of illustrative photorealism---plausible without being perfectly correct and without the polish and stylistic flourishes of "beyond photorealism" e.g. Frazetta's Conan covers.  Halfway to nowhere.

c) If I was flipping through cover art, I might linger but I would not stop.  There is a lot of content out there at that level.

Similarly, Boris Vallejo comes to mind as a great technical painter whose painted art always did nothing for me.  Too static.  Too posed.  The Jim Lee of painting. :)

Here's my recent - Issue 6 page 5. I use mostly pen and brush