And now, we add a new dlc were we help them get up on their feet and keep operational. Think of it like this, In broken steel, we eradicate them, blow them to smitherines, kill them. If they(Bethesda) decided that the actual canon lore have them dying out for good this time, then they can't just change it just to please some people.
But for something as major as the future of the enclave. It's nice and all that you can do sidequests and even mainquests different ways, but do you think that these sidequests will affect the next fallouts story? No. If there were to be a DLC or something where you can join them and do the whole story another way, that means that the canon lore will be split into two kinds of 'what if's'. Therefor there must be some canon storyline, compared to the options you get at sidequests which dosen't affect the whole fallout world as a whole. Ok, look, the Enclave are a major faction in the fallout universe.
