1. The barrier to entry is too damn high
In a setting like Railjack, the biggest problem is always making it out of the newbie zone, and for current railjack the only way to do so (without trading/buying from market, or joining someone else with an upgraded railjack) is to park the thing far away and play archwing only until gears and avionics are obtained. If they don't, they are subjected to the ship constantly being in the catastrophic failure state until revolite gives out, then they're sent back to the dock. With the new "aborting doesn't give intrinsics" rule set by DE to stop intrinsics farm, this takes the current new player experience and makes it even worse.
This is absolutely unacceptable. Something must give: either crewships/enemy damage on earth is lowered or basic max health/armor avionics are given out that can reinforce the railjack enough to take more than a single salvo of crewship missiles, because they have no option of outrunning them without high piloting intrinsics at their level. Having crewships simply shoot less often on earth is also acceptable.
2. Buff Archguns damn it
Because of the above-mentioned problem, archwing is the only way to get around early railjack content. Unfortunately, that only brings up the problem of how crap Archguns are to the surface. Hope you brought that Cyngas. If there's only two or three weapons with remotely comfortable time to kill, something's wrong, but everything's already wrong to begin with in Railjack.
3. Photors are still crap
I thought Pulsars were the worst weapon, but Photors are also bad. Look, an incendiary status that does a Damage over Time effect must be fine, right? No. The Damage over Time doesn't stack, so anything inflicted by the Photors (and, god forbid, any archwing weapons) will tick for piddly squat damage and may as well not exist. If we were talking about a shotgun style nuke like Cryophon, it would be worth it, but on the Photors? No.
If you switched the designs of Cryophon and Photors, I'd be very happy. A hitscan beam that freezes enemy fighters solid? Hell to the yes. A short range high-power fireball that inflicts damage over time? Awesome.
However, I don't think this is happening. So, the only way for Photors to be good, besides buffing their damage, is to buff Incendiary status effect. The only way I can think of doing it right now is to let it stack infinitely like how multiple slash procs can tick at once, or each successive proc multiplies the current ticking damage.
4. RNG stat drops, but only 30 wreckage slots
If the drops have RNG stats, 30 wreckage slots are not going to be enough if it is for every category of part combined. Now, if we were talking 30 slots for every different category, we wouldn't have this problem. However, this is also tied in with the next problem...
5. Repair costs are too damn high
Repair costs are too damn high. That means even if you get parts you want, you'll be keeping them for a long time while farming the mats to repair them. By the time you get enough, you would have enough intrinsics to make it to the next area, even without the Ivara farm. This means you can join someone else's railjack squad and earn better parts. As it is now, it is even possible to make it to the veil before gaining enough to repair a set of mark 1 parts.
The meta will ALWAYS be "never host until fully upgraded" until this is fixed.
6. Different roles, different rewards
The optimal way to play (and the method that DE seems to want) is to give each member dedicated roles. One is the away team, one guns, one handles the forge and repairs and the host pilots or something. Unfortunately, people rush to be the away when the POI has something they want or if they're trying to Ivara farm. If they want to farm intrinsics the normal way, it's better to be an Engineer and repair.
So, to encourage role diversity, ALL rewards need to be shared. That means affinity from killing mobs on crewship and affinity for repairing and forging. Yes, you can't share affinity that is multiplied through a stealth multiplier, but AT MINIMUM all drops that an away team picks up must be shared across all members. You already experienced this with Quellor and Pennant blueprints, now make it apply to all drops in Railjack. Resources dropped in any breakable containers, lockers etc. in the points of interest must be shared. Oh, don't forget that sentient ship too.