Looking at their route map:
http://www.ryanair.com/site/EN/dests.php

I could initially see why they were interested in standing room flights.
But then if you click a depature point, the distance is farther than I'd care to go.

Probably they would redo the schedule once they had those planes.

But overall a bad idea. (carry-ons ?, emergency exit times ?)
Would think China would have done it by now, they were manufacturing MD-80's for some time.

Sure I've stood in a Greyhound bus for 1.5hrs in my college years, but wouldn't now.

Prefer persuing the idea of triple bunk beds in the plane instead (previously posted).