I think alot of people would find it interesting. Couple things with it though.
1) I doubt Betheda would be able to pull it off so that playing as a super mutant, ghoul or other race besides human would be a unique and enjoying thing. It would most likely turn out to be pretty much the same as playing as a human. In that the game world wouldn't react to you as a ghoul. You might as well download a skin mod. Unless the game world is very different while playing as a ghoul, super mutant or other character, then there really is no point to it at all. I wouldn't want to be a super mutant had have everyone treat me as an average human.
2) Fallout is about humanity and its struggle to rebuild in the ruins of the old world. Ghouls and Super Mutants came from humanity but they can no longer count themselves as human beings. Why would a ghouls or super mutant want to help human factions? Why would most human factions what a mutants help? It doesn't fit fallout to have a none human protagonist, fighting for humanity.
3) This goes back to one. If it is done really well for each race, which would make the game radicaly different for each race. In a sense making a whole new game for each race, then the game would be very short. All that work could be better spent on other parts of the game.
4) One worry I have is Bethesda would throw in some "become human again" quest that would break canon.
If they made another Fallout Tactics or an MMO then I think I would be ok with it. But as an RPG with Fallout's history, I say no to the idea of playing as a mutant.
2. It completely depends on how the main story is written. And if a faction is in need of help why "wouldn't" they want a ghoul to help them?
"No, you're yucky, go away!"
"But you seem kinda screwed, you sure you don't want my help?"
"Yes yes we are very sure now go away."
"Erm... The opposing faction are raiding you, are you absolutely sure? I mean, they have Gauss Rifles and you have 10mm Pistols.."
"Scram zombie!"
Seems logical.
Anyway, as to "fighting for humanity", not really, it's about exploring humanity in the post-apocalyptic world, allowing to play as a ghoul allows you to explore humanity from a different perspective, so it fits perfectly fine with premise.
3. Again, the game does not have to be radically different, not every dialogue line has to be rewritten and rerecorded for ghouls, humans and trogs.
Let's take Goodsprings, none there seems to be a racist or bigot. From Sunny you'd get two additional comments on being a ghoul, from Joe Cobb you'd get the intro dialogue "What do you want,
ghoul?" and with Ringo he wouldn't aim at you when you enter the gas station as Ringo knows that PG's have no ghouls in their ranks.
Only major change to Goodsprings by being a ghoul would be Doc Mitchell's dialogue.
Not everything has to be changed just cause you are a ghoul, not everyone is a bigot or racist, and those who are aren't gonna just kill you.
It's been 204 years, people know that ghouls aren't zombies. (Except for the idiots in Capital Wasteland)
Sure enough the game should reflect your choice of race, so lots of NPC's will have new intro dialogues and have some small tweaks in other dialogues, while a reasonably sized number of NPC's will alter completely depending on your choice of race.
Manny for example would change completely with his dialogue if you are a ghoul. Hell, if you walk out in fron of the dinosaur before you talk to him then he's gonna shoot at you for being ignorant and not seeing you aren't a feral.
Boone would give you somewhat of a cold shoulder at first but would then open up to his usual dialogue.
The rest of the town, such as Ada, Cliff and Jeannie would have some small tweaks in their dialogue but nothing much.
No-Bark would have a few new lines if you are a ghoul but nothing as much as Manny has.
And Styles, this would work.
The game would reflect on your race, this case being a ghoul, without having every human go "KILL THE ZOMBIE!!!"
Some small comments, some new dialogue lines, and some NPC's (which are in a smaller amount but still big enough to make playing a ghoul different) would be completely changed depending on your race.
But the entire gameworld does not have to change.
Just a tiny part of it would have to radically change, say 10%.
4. If they do then we can always just ignore it. And if they say "It IS canon damn it!" then we can just go "Nope, it is not". Cause quite frankly if they do something like that then it's obvious they have no clue as to what Fallout is and we are more competent to decide what is canon and not.