I suspect Mobius was designed to compete with now defunct competitors that were going to supply screens for flexible, curved or roll up gadgets. Certainly plastic based OLED have shorter life and more prone to early failure than glass based OLED. The flexibility of plastic vs glass would seem to have a very limited advantage in a regular ereader with an Aluminium alloy chassis.
Edit:
Onyx Max Carta in 2017 allegedly has a flexible Carta Screen. See
https://en.wikipedia.org/wiki/Onyx_Boox#Release_dates
So Mobius wasn't just flexible, but was a generation. That article lists later Mobius Carta too. But the most recent Onyx listed (2023) at 13.3″ and 2200x1650 is the Tab with a Carta 1250 (better speed and contrast than the Carta 1200).
The original Mobius didn't have Regal waveform mode.