I 'd love to hear your rant about FO4. The people I have heard rant about it are usually the ones who hated FO3 too, so I did not expect to see that. I guess you wished for a natural progression from NV?
The short version is that New Vegas ruined™ Fallout 3 for me, and Fallout 4 turned out to be a watered down Fallout 3 from everything I had heard, and the first 20 minutes of gameplay are very much not engaging. I uninstalled after I killed my first Radroaches post-unfrozen.
Personally I've outgrown Fallout: New Vegas. I simply don't think the RPG elements, even with mods, outweigh the boring open world that you have to put up with. I'm just not a fan of the Bethesda school of open world games, and Obsidian didn't even bother to make the Mojave remotely engaging as a playground. It's like you are playing just to see the next NPC interaction.