While my personal preference is for text installers, I do recognize some benefits to GUI installers. The biggest advantage is that there's much better support for internationalization with the higher level programming environments associated with GUI.
I am not an expert in this area but it seems to me that options for text-only programming environments supporting i18n (and associated display of international charsets) are fairly limited and, to the extent they are available, have their own list of "non-universal" dependencies (libraries, bindings, fonts, etc) that is no less trivial than those of GUI-based programming tools. Because this i18n support is integrated into the development environment, the maintenance of code for a GUI installer should (at least in theory) be more straightforward than that for an equivalently internationalized text-only installer.
Even if the text-only tools for i18n are available and would not increase the level of "dependency hell", there is most assuredly a larger pool of potential contributors who would be familiar (or willing to become familiar) with the GUI development tools. I am sure it is possible to handle i18n with just BASH scripting, but the code would be rather non-standard and much less maintainable than a "higher level" approach (such as GAMBAS).
My personal preference -- being an English-speaking technophile who loves to see long lists of files being installed, hardware being probed, and whatever else minutiae that is happening on my 'puter -- is for text-only installation (CLI-based installation, truth be told). But, having said that, I feel that providing a mult-language GUI installer written in a higher level programming environment is better for the developers and maintainers of the distribution. As a fallback for cases where graphics hardware may not be supported, or even available, I would of course wish to have a text-only installer (and I think that "English only" might be a fair assumption for this alternative).