If you ask the casual fan its all about the CL anyway.
If you ask the players, it’s all about the CL too.
No one from abroad is moving to a big team in England because they want to win the FA Cup; no one is ever mentioning it unless they have been rehearsed to do so.
FA Cup is more important to fans of teams that are not in European competition, but how often are those teams in the final? Look at the prize pay outs with FA Cup compared to European competition. It’s not a money competition. Worse you have the League Cup, which is more or less the same competition so that itself is diminishing it.
The PL has become a lot less English, so there is less emphasis to win the oldest trophy. Also, it hasn’t exactly spurred teams on by winning it either. What exactly has it done for Arsenal? For United? It’s been a self-esteem trophy for them. It hasn’t kicked off anything, those teams are still both way below their standards. United starting to comeback a bit but Arsenal? It’s nice to win but in the scheme of things it hasn’t brought back the glory days. Wigan won it in 2012-13. How magical! They got relegated that season. Haven’t been back in the PL since.
It’s a novelty cup that relies on nostalgia. So yeah it’s a participation medal. It’s nice to win, but there are many reasons it’s not as relevant anymore.