On several occasions, Xavi said that Barcelona is serious about targeting this competition trophy. even one of their strikers, Lewandowski, once said that he and his colleagues had the ambition to win the Europa League trophy. so it's clear that Xavi really cares about this competition trophy besides prioritizing winning the La Liga trophy.
Barcelona and the other teams look financially to these competitions, as long as the financial prizes are much less than the ECL or La Liga prizes, I think they will focus on La Liga more than this one, and if they managed to somehow win it, that would be good for the name of Barcelona and could give Xavi and the other young players more confidence. On the other hand, the same thing applies to Manchester United, as I think they won't be interested a lot in winning this competition on the back of their rank in the EPL.