Ubuntu eliminated its text-based installer some years ago for its desktop versions. The graphical installer is designed to be run from a full (live) Ubuntu desktop, and there was not enough demand for the text-based installer (for the desktop version, anyway) to justify the effort and complexity required to maintain two separate versions, each with its own code and quirks and bugs and updates. The two installers used different methods to install Ubuntu, so the developers were also afraid it would result in a variety of "standard installations", which could confuse users and complicate technical support, troubleshooting, and software updates.
My guess is the message you are seeing is a vestige of the time when the text installer was still a part of the normal desktop ISO; you could report that message as a bug, if you'd like.
There is still a text-based installer for Ubuntu Server, the Lubuntu "Alternate ISO", and for the Network Installer (a very small ISO that fetches the majority of packages from online mirrors at time of installation, as opposed to fetching them from the DVD or USB stick). Of these, I would recommend the Network installer, as it is a relatively small download and will allow you to install a full GNOME/KDE/MATE/XFCE/LXDE/Unity desktop from the text interface.
I'm sorry to be the bearer of bad news... Please let me know if this answer was helpful, or if you have any further questions.