While CD (and to an lesser extend DVD) disks have reached the price-point of the floppy, they have one significant downside, it is WORM (Write-Once Read-Many) media, allowing it to be used only one single time, and you need to be explicit in writing the data to the actual media (you need to burn it.)
While CD-RW solves the "use only once" problem, it is still EWORM (Erasable Write-Once Read-Many) media, which still means you need to be explicit in writing the data to the actual media (you still need to burn it.), and also, you still need to be very explicit in erasing it. (simple delete is not possible.)
Okay, we can use a CD-RW in Packet Writing mode, however the downside to that, is that this mode is not very universal, and also, not the native mode of the media.
Now, while USB-sticks and SD-cards may not have the poblems of the CD, they have a whole other kind of problem: their PRICE! USB-sticks and SD cards are generally 10 to 100 times as expensive as diskettes per piece.
SD-cards, in addition have an added problem, because they need a reader to operate. While it is a very standard thing, it is not default equipment on the computer like the CD drive or USB port (or historically the diskette drive).
You wouldn't give out an USB stick or SD card with a 100 kB text file, not caring weither you would get it back or not.
So, to recap:
CD & DVD are basically WORM media.
SD cards and USB sticks are relatively expensive.
SD cards also needs special readers.
Diskettes have a very low data-rate
Diskettes have a very low storage capacity.
Now, is there a media out there that solves all these problems, or is there a way to get (very) small USB sticks or SD cards for a very low price (as they're the closest thing to diskette).