I love that the GOG installer is a simple *.exe file you run to install. But it would be even better if you could add an argument to the installer to install the game silently.
Kind of like what one can do with *.msi files, where you add /qb (shows the installation progress bar) or /qn (completly silent install) to install the software silently.
This is a cool feature which would allow us users to sort of create our own simple *.cmd/*.bat files or something similar to create a menu to install the game silently.
Other arguments that could be added is if you want Foxit Reader to install or not, and to set the installation path if you want it another place than the default.

Try "setup.exe /SILENT" or "setup.exe /VERYSILENT". I believe GOG uses innosetup, so that's what I searched for, and that's what I found, I haven't tried those switches myself though.

GOG likes to focus on being user friendly for it's installers.
user friendly = idiot friendly
meaning there's very little you could do to mess up an installation.
this silent stuff and the different switches, that is too complicated for most users and presenting it as an option will confuse idiots.

No need to make the installers more complex than they already are.
Only complaint I have is most of them still don't detect DOSBox 0.73 installed.

I don't see a need for a silent install, except in a corporate environment. What i would like is there downloader working so I don't have to install and launch every time i want to use it :P