The idea of using the Ruby On Rails framework to extend SAP apps and give them some prettiness potentially makes a lot of sense.
Culturally however the combination is very odd. Odd to the point of spooky.
SAP is the ultimate configurable enterprise system. R/3 is surely the most enterprisey system ever designed.
Ruby On Rails on the other hand is supposed to be the ultimate triumph of convention over configuration, beauty through simplicity and constraints.
I can easily imagine David Heinemeier Hannson in Walldorf telling a group of SAP engineers that BAPI is just too ugly to live. If PHP is the devil, then what the hell order of darkness is BAPI? We’d need to approach Cthulhu to get close to that level of evil. SAP is surely one of the great old ones.