not to mention you can't do the Vault 19 quest
You aren't actually restricted from this, those are identical to the ones from Primm and a different internal Faction entirely, despite the end of the quest giving Powder Ganger fame.
However, you
do get locked out if you kill Papa Khan for basically any reason.
You do get into the correctional facility though
You're locked out of this if you get negative reputation, not Karma. Access requires either skipping the Goodsprings quest for either side or some seriously scuffed stealth kills alongside some fame to even out the negative rep from completing the Goodsprings-aligned version of the quest.
Other NPCs are immortal and you can't kill them.
Ironically the opening sequence is one of the few times where there's only two immortal NPCs present- Amata because of fucking course, and the Mr Handy for...
reasons, i assume he's a support poster or something.
Everyone else will make a reappearance and the place is severely depopulated if you kill everyone possible (or let them get eaten by roaches).
That being said, the rest of the quest is a walking simulator and the only interesting outcome is destroying the vault in a way you can return to.
And Goodsprings is what exactly? You either kill Cobb or you help the town. That's it, nothing changes and it affects nothing after it.
It affects who you return to when using the town later (for the worse in some options), and does actually affect things after it as mentioned above.
You don't even get cool shit either way.
Starter quest. I'd say Leather Armor at level 2 or so is pretty cool compared to what's available, though not nearly so stylish.
You also get an extra quest chain or money* later on depending on the choice taken.
*Ringo has a habit of fucking dying offscreen but if he manages not to you get the cash.
No matter what you do, you can't even come back to the Vault since the devs didn't want the extra work of programming in actual player choice.
More of a bug in the scripts, but you can manipulate them to keep the vault open.
It's a story about a water purifier, then Fallout 4 starts and any INT 1 character can build one straight out of the vault. Let's not pretend like Fallout 3 is some forgotten masterpiece, because it isn't.
This is more Fallout 4's fucktardation than anything inherently bad in 3.
Don't get me wrong, 3 is still pretty bad for being set 200 years after the apocalypse and we could go over how every little bit of the game leads up to it being far better if set before the first game in the timeline, but it would be a constant repetition.