Some professional CD-i players offer a floppy drive so you can use a 3,5" disc to transfer data or to update drivers. These professional players were mainly used for either business purposes or in classrooms for educational purposes. The floppy drive was there for additional storage capabilities. It was used for driver updates but also for saving data that was created in professional applications like in classrooms: scores, values, to share it between players and in some cases between CD-i and MS-DOS.
cdifan used these floppy drives in the past during his time as a CD-i developer: "I think the floppy drives where used mostly for verification tests and quick program tests. You could also use them for getting screenshots etc. off the CD-i (provided your program could generate them, of course). I remember often using the floppy for preloading a RAM disk (on the 605 you can make these so they survive a reset) with basic OS9 system utilities like dir, copy, list...""we used them for tests. But basically, those were OS9 system floppies, it looked and felt a bit like MSDOS. So you could do i.e. file operations on a command line, just like DOS", according to a former CD-i tester..