Is gtk2 extension failing to create that directory when using the appbrowser on a "base norestore" boot? I had tested it on a clean boot. Pango is a dep of gtk2, and /usr/local/etc/ is a directory in the pango extension so the directory should already be there since pango would be loaded first, whether during boot or appbrowser load.
You are correct in that the gtk2 extension will not create that directory if no other dependency extensions have been loaded, though that should not happen. I normally use the "mkdir -p" option as a matter of practice, though I didn't with gtk2. I will add it in the script, though under normal circumstances the directory should be created as the deps should create /usr/local/etc.
Using the test condition simply prevents harmless error messages that would be seen when tce-load is used in the termimal, or during boot with the "showapps" boot code. Another way of course is using "> /dev/null 2>&1", but I prefer in principle not to try to create a directory if it already exists. Reducing even harmless error messages keeps the screen cleaner and saves time for folks who see the message and troubleshoot the cause to make sure it is not a bug.