Looking at this final should be a warning, along with what Barca has experienced over the last 2 seasons in the Europa, about how much of a nightmare this competition is for big clubs to fall in to.
When a big club falls in to the Europa it gives a chance for second tier clubs to make a name for themselves and there are a queue of clubs whose fanbases who make sure they don't miss that opportunity. We already saw that with Eintracht, explicitly, but United's game Vs Barca was also their best atmosphere of the season.
Sevilla, Roma have great passion for this competition in their fanbases. Add to them Feyenoord, Rangers and more and you can only conclude that whilst the Champions League is the completion of prestige, the Europa is the competition of passion.