Did the disco really have to save literal galaxy every season?

It really didn’t.

In Season 1 the only ‘save the galaxy’ thing is basically a one-off episode plot. Not unlike many other Treks.

Season 2, yeah. That flagrantly is save the galaxy.

Season 3, they are not saving the galaxy, they’re trying to help rebuild the Federation and its influence and uncover a scientific mystery. The Federation was crippled but existed and was at war with another group. Discovery shows up and is able to help with the use of a different perspective (a literal plot point) and new technology. The same thing happens in literally every Trek, it just switches sides on who has what tech. Enterprise was with basically everyone, SNW is the Gorn, TOS is the Klingons, TNG is the Romulans/Borg/Cardassians, DS9 is Cardassian/Dominion, PIC is Romulan Sect/Changelings/Borg, LD has the Pakleds and I’m sure that Prodigy has something as well. Haven’t started it yet. Either way, in all of them the primary ship that we follow becomes a primary plot point in the wars. The only one that doesn’t fit the mould is Voyager and that’s because they’re on their own but even then the show opens with Starfleet vs the Maquis.

Season 4, they’re trying to uncover another scientific mystery that is wreaking havoc in the galaxy. Personally i’d say it’s halfway there but not entirely. It’s more of a political season with seeing the internal struggles of the Federation. The ‘galaxy saving’ is a backdrop that’s set up for the inner aspects of the Federation being at odds with one another. It’s a representation of the struggle thats also within Burnham and all the crew members for being in a new place far from home. I honestly think that Season 4 is a work of art.

Season 5, saving the galaxy also isn’t a thing in this. Closest you can say is that they’re trying to save the Federation from being destroyed. Galaxy seems to be fine otherwise. But even then the season is more of a treasure hunt. A shitty one but still a treasure hunt.

Not a single time, not once, did the disco feel like just another ship in the fleet. It was always THE ship.

As opposed to any other show? As mentioned, every show features a primary ship that ends up solving the conflicts or being a MAJOR player in it. This feels like a really bizarre complaint. The four Enterprises we follow all feel like THE ship. Do they meet up with other ships? Sure, but they’re always the ones at the heart of the conflict and solving it. That’s… how shows work? It’s not like the new tech for Discovery is a big deal or not used as a constant plot point either. DS9 had the Defiant with a cloaking device that was heavily relied on. Why? Because that’s what they had. Discovery has a spore drive which is why it’s being used so much and why we follow it. Just like the Enterprise had its name or new path, Voyager had it’s stranded space and DS9 had a new quirky ship based around a space station.

I really love all the worldbuilding in Trek, but in disco that always played second fiddle to whatever crisis was going on, which the disco would then inevitably resolve.

… what?

I feel like you have completely missed the majority of what was happening on screen over the course of the show. The crisis is the second fiddle to the characters. It’s used as a vehicle to drive character development as opposed to having characters drive a crisis like in TNG or Voyager. Not that both didn’t have character development as well, but they were often static characters that were reacting to a new crisis each time. Discovery flipped the switch hard and went all in on serialization and character development. Every season the characters change and grow, so much so that they did a really shit flashback to what their characters were like about halfway through Season 5. The characters were fleshed out by the worldbuilding and they themselves fleshed it out.

In Season 1 and 2 they were relatively constrained about what they could world build but they still did their best. They expanded on the engagements with the Klingons (which annoyed some people but I enjoyed), expanded on Prime Pike for the first time since TOS, they finally gave Number One a name, they expanded on the childhood with Sarek that Spock had and his relationship with his human mother that he’s hinted at, expanded more on Section 31 and expanded further on the Terran Empire. They developed an entirely new race in Saru and developed a whole culture around him that stretches across multiple seasons. Then they went to the future where they have more free reign and went nuts with developing incredible looking ships and insane tech and new worlds and new empires and elaborating on cultures not seen since TNG.

How is any of that second fiddle when every bit of that expansion was the driving force of each season?

I see these complaints all the time and I don’t understand what y’all are talking about, especially when every other Trek show is guilty of the same ‘crimes’.