Bethesda makes great games, but they definitely have their technical issues. They're great for locking up your console that's for certain.
Could they be way better.... well yeah. But they're definitely playable.
New Vegas probably has the best "repeat playability". I think I played through that one 3 times. It's got just enough that you don't mind starting back over with nothing. F3 and F4... when It's exhausting just to think about starting over when I look at how much crap I have to do again. Part of what was awesome about F4 was going into the world not knowing what you're going to run into or see or find. It's like an M. Night Shyamalan movie. Yeah, you can watch it again, but the surprises that make it exciting are only good once.
Nuka World doesn't look like anything special to me... I'll get around to it eventually.
I'm bouncing back and forth between F4 and Destiny these days. I went back to F4 to play with all the new building stuff and to finish the Institute storyline. I felt really bad about killing everyone in the Railroad. Not so much with the BoS though. They're a-holes anyway.