Fallout 4 took over 3 years to make and reused skyrim assets.
NV still had way more depth and detail than F4 and it only took Obsidian 18 months,
Imagine if Obsidian had over 3 years to make NV.
I can see why Bethesda tried to forget Obsidian over from the beginning. Obsidian is an actual competent developer.
You can keep retreading this point as much as you want, you still don't get why it took so long and you won't get it. Bethesda is working with the same engine they used for Morrowind. The reason why development takes so long is partly because of this.
Fallout New Vegas, for as much as you put it on a pedestal, was not really that much of a change from Fallout 3. It used basically all the same assets, all the same gameplay mechanics and only deviated in small, easily-made details. The minutiae that differentiated the games so much in your opinion ended up being wholly inconsequential details in the manner of game development, like removing the "Cannot die" flags from NPCs, or tossing in more speech checks.
Development time rarely is the factor for the quality of a game. It took Bethesda 3 years to make Fallout 4 because it took 3 years to make Fallout 4, that's all the point that needs to be made there. It isn't because they're a bad company, but because the workload of making Fallout 4 ended up taking three years. If they could have done it in three months, they would have done it in three months. But it took longer.
