Being able to build a simple interface on top of the few commands they use, so they don't have to remember flags, argument orders, etc., would be advantageous to us all (and require less support on my part).
Also, what is possibly wrong with someone trying to make some money for their work??
Second of all, learning shell scripting is an almost ridiculously important skill. Wouldn't it be better that you sit those devs down and have them go through a couple hours of intensive shell boot camp so they don't need your help anymore? Anyone who's a halfway-decent dev can learn the basics of shell (simple scripting, variables, redirection, piping) within a couple of hours, easy.
Haven't you ever come back to a piece of code from a month ago and had to reacquaint yourself with it? (I know I can't be unique in that... ;) ) We cram an awful lot into our heads as devs, there's no room for things we barely use from a month ago.
To you, the shell may be perfect. For someone else, it's a severely antiquated method of input that was outdated after Windows 3.1.
I love me some shell, but that's you and me. Not all devs.
Edit: reminds me of CPR class. After a month or so, you better brush up lest you actually need to use it!
Maybe your terminal problem is solved (mine is), but their problem may be different.
Would you tell people who made chrome to quit back then, because the browser problem was solved? (IE, Opera, Mozilla Firefox) Or maybe tell Google to abandon drive and Microsoft onedrive and all that smaller companies like SugarSync to drop it because Dropbox has "solved it"?
This also means that indeed your previous question is good: it'd be nice if the author could explain the use case and business case for his terminal, seeing that we have a number of others around. (Google explained why Chrome with a comics thingy and got me immediately). But your questioning sounded like the author was already in err.