Because having your wife/husband and son killed/stolen from you isn't a reason enough to save them.
We needed a dam to fight over and fallout 4's story would've been fantastic
The dam battle was a terrible rendition of what was supposed to be an epic battle and a grand finale to New Vegas. Sadly the limitations of the engine and just kinda bad design of the actual levels of it and encounters within it made it annoying as fuck. At least in the end you got to either talk down the opposing leader or just kill them and then kill the other one too because why the fuck not I guess.
But the reason why it's still kind of great is because all the things you worked for within the game do make an appearance. Boomers do a bombing run, the Enclave/BoS assist you, the Khans are either present on one of the sides or are gone, the securitrons make an appearance. It's a great capping off point that reflects the choices you've made through your play-through.
Speaking of which, that's why the ending slides aren't just a random thing that is plopped at the end of NV because the fans wanted it/tradition, it's a great (the best actually if budget and code issues are of any concern. If they aren't the best is to actively represent those choices within the game world) way of wrapping up an open world RPG game with lots of different choices and ways of going through the story. It tells you what happened to the people you've met, the places you visited and a bit of the fate of the world at large. It wraps up your play-through neatly and gives you some down time to reflect upon the adventure you had and a feeling of satisfaction at
a life well lived a game well played and furthermore, it makes you wonder how different choices would be reflected, if at all.
Witcher 3 did it as well, as did STALKER: Call Of Pripyat. And both of those games were better off for it.
Because having your wife/husband and son killed/stolen from you isn't a reason enough to save them.
I carried the wife's wedding ring with me right up to the end.
And nobody ever comments on it...
And no one talks about the platinum chip after it gets used for Mr House's death robot army.
It has served its purpose and as such has no more use. Plus, the only people that know of it are you, Mr House, Benny and Yes Man. Also the courier company manager, but he has no idea of its true purpose so talking to him about it is pointless. Benny and Yes Man similarly have no real clue of how it actually works apart from "it activates the hidden securitron army and upgrades the existing securitrons".
The ring in Fallout 4 is a band of metal with scant real value apart from sentimental and I see no scenario in which someone might bring it up except a few highly specific situations for which the game wouldn't be any better or worse off. Fallout 4 has its fair share of writing problems. "Nobody notices your wedding ring" isn't one of them.