Some installation tools are now advertised with slogans like: it “is not necessary to learn any scripting language to create setup programs”, “all options can be set with a user-friendly graphical interface” or “no programming required”. 

Apparently installation tools only sell if you promise to programmers that they do not have to program! Is installation so difficult, or is it not important enough?

Is installation so difficult? If you create an Installation you need to understand it anyhow. To understand the installation process it needs some study, but the complexity is trivial compared to all the other things a programmer has to know and to do.

It is not important enough?  Of course it is very important, maybe it is the most important part of your program, because installation is the first impression of the users, and at the same time the most frustrating part about working with computers. Users need to answer technical questions they would normally prefer to ignore. And if it is not done right, it is also the most costly program; help desks spend a great deal of time on it.

So, knowing this, why should installation tool vendors suggest that their installation tool does not need any programming at all?

The answer is that it is easier to create an installation tool that does not have scripting. It is also easier to create your own scripting language then for the same general purpose language a Developer daily uses.