A thin installer is a program that will download the actual program that you install. So you download a few megabytes from a website. Then you execute that program and it will start fetching the actual program you want and installs it. I have seen this in numerous places:
- Google Chrome
- Atom Editor
- Starcraft 2
The problem I have with those installers is that I cannot download the whole thing with a fast connection and reuse it later on. The creators just assume that I have a fast connection available where I install the program. But that is not really the case.
During the C programming course that I tutor, the participants need to have some sort of text editor in order to write their code. The course is often held before the semester starts, so the participants are prospective freshmen. They do not have university accounts yet, therefore they cannot use the university wireless network, thus have to work without an internet connection. The tutors distribute the software on USB thumbdrives. When software is only offered as a thin installer, there is not much I can do, I just cannot use it.
The internet connection I have at home is way slower than the one at the university. For downloading large game assets (like Witcher 3), it is preferable to download them there. Since I bought the DRM free version of Witcher 3, I was able to download the regular installer from GOG. I did so at the university, transferred it to my desktop PC and installed the game. But for Starcraft 2, I only got a thin installer. At home I still had to download 40 GB worth of data, which took hours.
There are some cases where I can understand the thin installers: Device driver installers often download gigabytes of potentially suitable drivers, then install the one correct one. There a thin installer makes sense as it removes the needless download of unneeded drivers. Letting the user choose the right driver might work, it is just way more convenient to have a little tool choose it for you.
I would prefer regular installers most of time, but I fear I won't get them for most software.