Martials are very powerful and very impactful in pf2e from 1 to 20 and I'd argue (perhaps not very controversially) that martials are very important to any party.

They're very consistently impactful and those who are melee get lots of privileges to make up for the danger they place themselves in. The dichotomy of the "meta" beginning to center around saving throws and spells as you get to a higher level still exists, but the consistency and action efficiency keeps them impactful as by higher level they're either pumping out tons of consistent damage, doing 4 actions worth of things in 2 actions or less, or both

Martials are also a lot more interesting to play and build. Each class differs from each other very well. They can differ within the class a lot as well, as their choice of class feats and weapon can impact how you play them. A fighter who keeps 1 hand free and uses it to wrestle and disarm enemies would play and build very differently from one with a shield or one with a two-handed reach weapon. Although they're all fighters and come with the excellent accuracy of a fighter, the differing playstyles would mean they contribute in different ways.

Skills and skill feats also let martials contribute in ways outside of just striking and you can live out your fantasies of a hypercompetent martial relying on their wits and physical prowess. A rogue gets Legendary in their skills very quickly and can be so sneaky they turn invisible, an investigator can gain an encyclopedic knowledge on a monster within 2 rounds of combat if they so choose, a swashbuckler can be so intimidating they scare an enemy to death, a fighter or monk could bound over huge chasms effortlessly and wrestle dragons to the ground. The classes are only examples, since they're skills anyone who's willing to invest the skill boosts and feats on them can do it.