It's difficult to talk about the problems Fallen Order has right now because it's fair to expect a great many of them to be fixed in upcoming patches. The frame rate dips, long load times, pausing, and bad textures are all well known issues at this point, especially on console, and it's likely Respawn has some fixes in the works. A major problem Fallen Order has that will never be fixed, though, is the underdeveloped and disappointing customization system.
In true Metroidvania fashion, you'll be able to re-explore previously inaccessible areas of the game to hunt for treasure. While revisiting planets with new abilities, you'll occasionally find segments of health upgrades, segments of force meter upgrades, and stim upgrades (the "estus flask" of Fallen Order). There are a small handful of these items scattered throughout the 5 returnable planets in the game, but those upgrades are not what you'll find in 90% of the games many, many chests.
Instead, what you will find for taking the time to explore, back track, and face optional bosses are a plethora of cosmetic items from 5 categories: Ponchos, Outfits, BD-1 Colors, Mantis Colors, and Light Saber parts.
Each and every one of these unlocks is purely cosmetics and only the light saber parts have unique models. There are 23 are the same poncho with different colors to collect, 5 of the same outfit with different colors, 16 color palettes for BD-1, and 14 color palettes for the Mantis. The lightsaber parts come in 4 types: 12 emitters, 18 switches, 18 sleeves, and 26 materials.
Again, none of these things do anything.
While it is definitely fun to work on your lightsaber on the bench, switching out parts and customizing like a badass Build-a-Bear Workshop, once you leave the menu you can't actually tell what you did to your lightsaber. I mean, your hands cover up the parts you customized and your swinging it around the whole time, so you can't ever see it anyway.
It's obvious this wasn't always the case: you'll find a of lightsaber parts called Honor And Wisdom 1 earlier on, and then later a set called Honor and Wisdom 2. Clearly, at some point, these parts were meant to actually be gear with stats or perks. Why this didn't make it into the game is maddening.
Instead, your only sense of progression is through the character skill tree. There are 3 skills each that increase both health and force meter, why weren't those upgrades linked to lightsaber parts or ponchos instead? There are any number of perks these cosmetics could have had: lightsaber reach, stamina recovery, projectile deflection efficiency, movement speed, the list goes on and on. Instead, there are 132 items to collect that do nothing and look terrible.
The problem isn't so much that the collectibles are tacked on - after all, the relics you collect in Uncharted do nothing but unlock cheat codes. This is a cinematic experience that doesn't necessarily require progression. The problem is actually how these collectibles tie to exploration. This isn't a linear game with short side paths like Uncharted, this is a full scale Metroidvania, and to be honest, returning to past planets to scour every inch of it for another ugly poncho doesn't sound very compelling.
In Super Metroid, every single item you collect is a power up. Some are relatively minor, like +5 to your max missiles. The increase from 155 missiles to 160 isn't especially meaningful, but it is nevertheless a power increase. The collectibles in Fallen Order aren't just useless from a power perspective, they aren't even particularly interesting cosmetics worth hunting.
The lack of a gear up system would be an easier pill to swallow if there wasn't a seperate RPG-esque progression system in the skill tree. Drake has no power increase at all, and that's core to Uncharted. Having a weak upgrade system in Fallen Order is worse than not having one at all.