This has been a thing in Fallout since the beginning.
Fallout 1,Find the Water Chip or your Vault will die of thirst.
Fallout 2, Find the Geck or your village will starve and die.
Sure, but the way those storylines are structured exploration is organically integrated to the game's core. You don't know
where the water chip or GECK are, you don't have anything besides a couple of pointers to go. Finding the things requires you to explore of your own volition, and across the way find out more about the world. Hell, the first game even has a time limit, and many people hate it, but it works well make you feel the pressure and get invested in your quest. As opposed to F4, where you are basically given your lead from the start, and all you have to do is follow it.
Not to mention, both of those are 20 year old games at this point, and one would expect VG writing to progress rather than regress
Fallout 3, Find your dad who abandoned you.
And Fallout 3's writing is terrible, so no surprises Bethesda didn't even bother to improve on their already shit formula. But hey, you got more time with your Dad at the start of F3 than you do with your baby for almost the entirety of F4, so it's actually gotten worse, not better.
Fallout New Vegas, Find the Guys who shot you in the head.
I mean, isn't that good enough? A guy shooting you in the head while taunting you isn't enough of a personal motivation to get to Vegas and shoot him in the head back?
Brotherhood - Synths bad, destroy synths.
Railroad - Synths misunderstood, help synths.
Minutemen - "A settlement needs our help"
I may sound reductive, but take for example the Legion in NV, who though largely being almost cartoonishly evil, you get to talk to Caesar and listen to his grand plans, and though his idea of dialectics is completely false you get something a lot more sophisticated than just a roving band of roman LARPers. Hell, let's not even go with a major faction, let's take the Great Khans for example. At this point, after having their shit kicked in for generations, the Khans are reduced to a small band, making drugs to survive. Their great raider past is long gone. What do they do now? Do they join the Legion and survive individually, even though it means their "death" as Great Khans? Is there point in sticking to their tradition if it leads to a dead end and their deaths in general?
Not to mention that all of the factions stories tie in to a greater theme of old world nostalgia building something new instead of repeating the mistakes of the past.
Fallout 4, meanwhile, has no real characterization or themes to it.