It is if you want to remain competitive in the long run. And if you want proof of that look at Arsenal in the PL and CL this season, and continually bombing out of the CL early doors. Failure to make the CL could come back to haunt you in an ability to get deals done this coming Summer. Players who want to play in the CL, and that generally means the better players, won't consider moves to clubs that aren't in the CL unless they are going to pay them a ridiculous amount of money for not being in it (and that's only United and City in the PL).
It's utter nonsense that qualifying for the CL is a big draw for top players though, even if you manage to qualify year after year, and Arsenal are probably the highest profile example of that. The only clubs that top players want to move to are those that they believe can win the thing (and pay them top dollar while they help them do it). It's the reason Suarez and now Coutinho left Liverpool despite your CL qualification, and the reason top players aren't scattered among the likes of Shakhtar, Basel and Porto, despite their presence in the CL every season.
Maybe it's just because I live in the UK, but I never hear any talk of Bayer Leverkusen finishing 4th in Bundesliga or Villarreal finishing 4th in La Liga meaning they're suddenly in the market for top players, it's only in the Premier League and is blatantly not true.
Yep. Almost there. I wasn't actually referring to Liverpool though (however maybe 2005 and 2007 makes an argument against your claim, but that wasn't my point).
It was to counter the claim that winning domestic cups lays the foundation for greater things which of course it doesn't do anything of the sort (ask Arsenal). Domestic cup competitions with games that often consist of squad players against non-PL teams are nothing like European cup ties and have absolutely zero to do with challenging for the PL. Unless of course people believe that adrenaline stays in the bloodstream for far longer than scientists have established
It breeds a culture of winning and performing on the biggest stages, and proves to the players that they're capable of digging deep when the stakes are high, which is something especially important for young players who haven't had those experiences before.
When United won the League Cup last season, it ended our longest run without a trophy since Fergie's first three season's in charge. We'd gone two seasons without silverware.
The first silverware we won under SAF was the FA Cup in 1990. After that it was the CWC in 91, and the League Cup in 92. None of these were a league title or a European Cup, but they were trophies. A tangible goal turned into a concrete memory. In 93 we won the league. From winning the FA Cup in 1990 through to winning the League Cup last season, United have failed to win silverware in just 7 of the 28 seasons. We won 8 of the first 11 Premier Leagues between 1992/93 and 2002/2003, and won 3 FA Cups and a CL. We then had a period of major transition and failed to win any of the next three league titles, which was the first time since the inception of the PL we'd gone longer than a season without lifting the title.
However, we did win the FA Cup in 2004, our first since the treble in 98, and the League Cup in 2006, a trophy that was particularly poignant because it was a trophy won without Keane, who's departure marked something of a new era at the club. In 2007 we won back the league title, followed that up with another in 2008, as well as a CL, and won the league again in 2009. We failed to win the league in 2010, but won another League Cup, then won the league again in 2011. 2012 marked our first trophyless season since 2005, following which we won the league again in 2013, at which point Fergie retired, ushering in another new era for the club. No silverware was won in Moyes' season or van Gaal's first, but we won the FA Cup in 2016, and the Europa League and League Cup in 2017, these trophies marking the first tangible successes in United colours, if ever, for much of our squad.
When the chips are down and a manager needs to rally his squad, possibly even in a cup final, what's going to be more stirring? Evoking memories of lifting a cup the season before, or talking about an away win at Stoke to secure 4th place? When new players sign and new academy graduates join the first team, what garners more respect? A collection of winners medals, or tales of grinding out a 0-0 at the Emirates to keep Arsenal at bay in 5th?
It's also funny that you bring up Arsenal, because even though it was before Wenger started, they'd won an FA Cup, a League Cup and the CWC in the years between their league title in 91 and his first success in 98, as well as winning the FA Cup in 2003 between titles, and again in 2005 after they went unbeaten. Their downfall then was the lack of investment while the stadium was built coupled with the emergence of Russian funded Chelsea knocking them off the top table.
It's not about maintaining an adrenaline rush for a year, it's about cultivating the attitude of winning at all costs, not giving up, and believing that you truly deserve to win, so that when it matters, players will run through walls to ensure they're the ones celebrating come full time. Fergie won 20 of 26 semi-finals United appeared in under his leadership between the domestic and European cups (CL, UC/EL, CWC), and of the 20 finals, we won 12. We're now 23 for 29 in semi-finals (79%) and 15 for 23 in finals (65%) since Ferguson took charge, with us being fairly consistent throughout with the win rate. Liverpool are 18 for 26 with semi final wins (69%), and 10 for 18 in final wins (56%) over the same time frame. However, in the 11 seasons prior to this one (i.e. everything after your last FA Cup win), you're 5 for 9 in semi finals (56%) and 1 for 5 in finals (20%). The 11 years prior that (1995/96-2005/06) you were 8 for 10 in semi-finals (80%) and 6 for 8 in finals (75%). Even with the slight skewing from the three you won in 01, that's a remarkable drop off for a similar number of semi-final appearances. Your average league position between 1995/96 and 2005/06 was 4th. Of the 11 seasons, you had one 7th, two 5th, three 4th, four 3rd and one 2nd placed finish. Your average league position between 2006/07 and 2016/17 was 5th, but you finished 8th twice, 7th twice and 6th twice, with two 4th placed finishes, a 3rd placed finish and two 2nd placed finishes keeping the average up. Despite reaching the late stages of competitions almost as many times, you've won five fewer trophies, and at the same time, finished outside of the top four positions twice as many times.
Of course winning FA Cups doesn't guarantee that league titles are around the corner, but if you have a squad containing a number of players with cup winning experience, it means you've got a squad that knows what it takes to win in big league games and bigger cup ties (e.g. CL semi-finals and finals).
The fact that in 2018 you're still pointing to a lost final in 2007 speaks volumes about the attitude that's pervasive not just through the playing staff at Liverpool, but the fan base too. The same attitude that keeps you pointing at the two lost finals in 2016 as a sign of "progress".