I think that having both groups share the traits of a singular origin and no ability to reproduce is exactly what annoys me.
It is kinda weird that we have two groups of long-lived beings that can't reproduce - yeah.
But also, I think the reason I don't have a problem with it - Is because if Ghouls are very old, like to the extent that there are people who lived long before the bombs dropped who are still living 200 years after they dropped - Having them be able to reproduce just like normal humans would kinda make them an obvious replacement to humans in the way Supermutants were meant to be - Long-lived, radiation resistant and capable of reproduction.
The "All Ghouls are old Ghouls, we're the first and last generation of our kind" stance Tycho has I feel resonates more - They are very old people, and in a sense, the ghosts of the old world still around and haunting.
Plus, I know this is paratext, but Tim Cain's explanation as to why both Ghouls and Supermutants are infertile makes sense: Ghoul's DNA is mutated in the more conventional sense - Being broken - And therefore cannot be passed on, whereas Supermutants DNA has an extra strand and is more resilient, but as a result cannot be passed on in the same way normal DNA can.
It's also not apparent that within Fallout 1, Ghouls only come from Necropolis.
It's not - But the fact that Necropolis is the city of Ghouls is what makes it meaningful.
Like - It would be kinda meaningless to say "This is Necropolis - The City of the Dead" if every city had some level of walking corpses wandering the streets.
to say nothing of Harold and Talius (and frankly the less said of them the better).
Why? Harold and Talius are just kinda unique mutants that were created in a way separate to other mutants.
I don't see the issue with that - Like having a few mutants who are similar to other types of mutants - but biologically unique, and with unique origin stories is kinda cool. It makes Mutation more chaotic.
Even internally with Fallout 1, nothing unique happened to the Vault 12 dwellers to warrant their mutation being a one-and-done scenario. They were exposed to radiation, but not directly via a nuclear blast, which the later games seem to think is necessary to create a Ghoul (i.e. a Ghoul is born when a human survives a short but intense dose of radiation). Why exactly can't people elsewhere in the world be exposed to radiation in a similar way to Vault 12 and not become Ghouls?
I agree with it not being a one and done scenario.
But also - I like the idea that the types of Mutants you encounter aren't just uniform across the entire Wasteland.
Like - Why should every group of people that's exposed to radiation turn out the exact same way and with the exact same traits? If you had it so it was like - This city was nuked so it's inhabitants were turned to Ghouls, and this city was nuked so it's inhabitants were turned to Ghouls, and this city was nuked so it's inhabitants were turned to Ghouls - Like "Ghoul" was just the generic type of mutation that occured with radiation
1. That would make Ghouls seem less special - Meeting the Ghouls in Fallout 1 is less memorable if Ghouls are literally the most generic type of Mutant around
2. It also makes Mutation - Something that's inherently chaotic - More uniform and less innovative.
Like, for the second point - Think of it like this: When Ghouls were introduced in Fallout 1, they were this totally new type of Mutant made for this game - They were something totally unique that the player had never seen before. Now in every subsequent game they've become something generic - The default type of mutation that humans go through.
I would rather it if it was like - This city was nuked so it's inhabitants are now Ghouls, this city was nuked so it's inhabitants are now underground dwelling mutants who barely look human - This city was nuked so it's inhabitants now have big arms, and crag like pincers - This city was nuked so it's inhabitants are these strange tentacled creatures, this city was nuked so it's inhabitants are now slime-like creatures, etc., etc.
Like if we're populating the world with fantasy races, why does it have to be the same exact three ones everywhere you go? There are Humans, Supermutants and Ghouls in California, and Humans, Supermutants and Ghouls in Washington DC. The world would feel more unique if Radiation resulted in lots of different types of localised mutants - So the result of what happened to the people exposed to it was different depending on where you were.
This is at least consistent with the weird edge cases
Again - Why do Harold and Talius need to follow concrete rules?
There being weird edge cases where it's unclear what specifically they are is good - Mutation shouldn't be a consistent thing.
The Master is a weird edge case - He was dipped in FEV and became this lovecraftian horror - A mass of flesh made out of multiple bodies. Same with Centaurs - What are Centaurs? They're these masses of walking flesh that are the result of just dipping a bunch of unrelated shit into the Vats and seeing what happened
Supermutants are the result of perfected FEV - Before the Master I imagine FEV just produced a bunch of weird incoherent monsters, and Talius and Harold are just the last of those.
Harold and Talius not fitting any specific mould, but being their own unique edge cases is a strength not a weakness.