The positive thing from Liverpool's defeat in the FA Cup could be that Klopp can focus more on his squad to be able to play better in the competitions they are still participating in, namely the Premier League and European League. Moreover, currently the condition of the Liverpool squad is not completely fine. Several players are still injured and several main players are also susceptible to re-injury because they are just recovering. So focusing on the Premier League and European League may indeed be the best way for Liverpool.
Yeah reasoning it on that dimension is better for Liverpool to win other major League than the FA cup because the current leagues they are playing now is even more better than the FA cup, so perhaps like you said I think is better for them as they were kicked out of the FA cup so that they will be more focus and gather all there strength and energy to their current leagues because playing on several leagues could sometimes affect the performance of a club because there would be no much time to have enough rest so with that there could more possibility of the players to sustain injuries. Also Klopp should be able to identify the reason why Liverpool was performing the way they did on there match against Manchester United and rectify it so that it will not repeat again because they cannot afford to lose any match on this premier League do to the competition they are having with Arsenal and Manchester City so they need all the consistency to remain on the trend.