At some point during the 2.x dev cycle, the Gnome people removed an important feature from gnome-terminal, on the grounds that it might allow a user to make some of the icons in their UI look inconsistent the desktop-wide "icon theme," which is somehow more important than making it possible to distinguish between different things.
For a while, I simply downloaded the old version of gnome-terminal that still had the feature and compiled that myself, hoping maybe the whole stupid "icon theme" thing would blow over and someone would see sense. This did not occur, and when I upgraded to wheezy at work it became More Trouble Than It's Worth to try to compile the old gnome-terminal, so I switched to Konsole, which still has profile icons. I'm happy with this solution, because gnome-terminal was one of the last remaining vestiges of Gnome that I was still using, and frankly I'd just as soon move away from all of Gnome. Since sometime around version 1.0, Gnome has been systematically removing features and options and configurability at a rate that would make Apple blush. So good riddance.
But people who are not big terminal-window users keep asking me why on earth I would ever need profile icons. I want to have a post I can point to that answers this question. So I took a screenshot of my home desktop (which is spread across two monitors) and snipped out the two taskbars (one from each window) to show off here. I want to stress that this is not a contrived example. Somebody on IRC asked the question, and I took a screenshot, and then I wrote up this post. Here's my main taskbar:
The three icons at the left are Run, Screenshot, and a colorblind thingy. After that there's a small blank space, then the task list, which contains the following, from left to right: Totem (a media player), dclock (the really generic-looking icon; this clock is positioned on the main monitor but often gets covered up by windows), Seamonkey (my main web browser), OpenOffice.org Writer, Opera (another web browser), Emacs, a gnome-terminal window (this computer hasn't upgraded to wheezy yet) that I use to tail logfiles, a gnome-terminal window that I use to play a game called Brogue, a gnome-terminal window that I use mostly for playing NetHack (another game) on NAO, a gnome-terminal window that I use for generic shell-related purposes, but in an auxilliary fashion (not my main shell profile), a gnome-terminal window that is remotely connected via ssh to a web server, a gnome-terminal window that I use for mostly NetHack-related purposes, but which is different from the other one (it's not for playing on NAO), another Seamonkey window, Chromium (another web browser), a gnome-terminal window that I mostly use for NetHack4, a text editor, a gnome-terminal window that is connected via ssh to the computer upstairs in the living room, a gnome-terminal window that is connected via ssh to the router, and a gnome-terminal window with a root (administrative) shell.
Here's the one from the second monitor:
The tasks on the tasklist here are a gnome-terminal window that I use to run a Perl script I wrote that reminds me when I'm supposed to be going somewhere or doing something, two more instances of dclock (these are positioned on the secondary monitor where they're less likely to get covered up by other windows), a gnome-terminal window that I use for interacting with MySQL (a relational database), two volume control applets (probably because I forgot I already had one opened and opened another; these things happen), and finally the gnome-terminal window that I use exclusively to run irssi (an IRC client).
It's important that I be able to tell different terminal windows apart on the task list. For example, if I'm looking for the web server window, I do NOT want to fiddle around with opening up six different game windows and three windows that are shelled into other systems besides the web server plus various other utility windows before finally finding the right window. This is what window icons are for. If anything, the difference between some of the terminal windows (particularly the ones used to ssh into other computers) is more important than the difference between e.g. a web browser and a word processor. Being able to quickly find the window I want is important, because otherwise hunting for the right one would cause me to waste a lot of time, and I'd get a lot less useful work done. Without profile icons, a lot of what I do would take 3-5 times as long as it should, sometimes more, because hunting for a lost window has a tendency to break a train of thought at unfortunate times.
For those who were not keeping count, the total number of gnome-terminal profiles visible on my desktop at this moment is thirteen. This is typical for me at any given time. About half of these windows are usually open, and the other half just happen to be open at the moment. Actually, my single most-frequently-used profile, my generic shell profile, isn't shown, because I don't happen to have any of those open right now. (I open them whenever I need one for something. Sometimes I have 2 or 3 of them open, but right now none. If I get more than about 4 generic shell windows open, I change the profiles on a couple of them to make it easier to keep straight which is which.)
Altogether, I have some 40 different terminal profiles, most of which are not in use at any given time, but they all get used sometimes. Every single one has its own icon. Most of them really NEED to have their own icons; a few (like the different NetHack windows) could probably do without. My situation at work is similar, in principle, though of course the details are different. At work, I don't have game windows; but I have way more shelled-into-another-computer windows, plus multiple distinct logfile windows, multiple distinct database windows, etc. If anything, the total number of terminal windows at work is often larger.
This is why profile icons matter, and this is why I don't really have any use for recent versions of gnome-terminal. This is why I am switching to Konsole.