Depends what you see as objectively. If you consider Fallout 1s gameplay, its concepts, the developer quotes, design documents - most of it actually here available at NMA even! Go and look them up, the history of Fallout! Than would you really say that the changes to a first person shooter with only the bare minimum of role playing elements keept inside is, objectively of course, an improvement to Fallout 1?
I know enough of the history and have played 1 and 2 (again the incorrect assumption is if you like 3, you didn't play 1-2. Wrong.) since it is an opinion on something you can't claim opinions are objective. They're subjective. You may dislike everything about it, but that isn't objective.
Especially when you're trying to compare entirely different game styles.
And that is the error.
You can objectively say that Fallout 3 and Fallout 4 are not an improvement to Fallout compared to Fallout 1 and it's history. That doesn't mean that Fallout 3 and Fallout 4 have to be bad GAMES.
Maybe Fallout 4 will be the best first person shooter humanity has ever seen so far, but that isn't the point!
I will say it this way. You order a grilled steak. The chef gives you a cooked chicken. Can you make objective statements about this? Yes you can!
I think you can objectively deduce that chicken is not steak, right? So you can also say that a chicken can never be an improvement to a steak, if what you want and what you expect is a steak. It could be the best cooked chicken in the world even. But it would still NOT be a good steak, would you not agree? And now you explain this to he chef and he pokes you in the eye with the fork and dissapears in the kitchen. And this pretty much sums up most debates about why Fallout 3 and 4 are not improvements over Fallout 1.
The fact that Fallout 3 and 4 have entirely different game styles is the whole point of it. And to say that Fallout was never meant to be a "first person shoter" is not an opinion, and it is not subjective. How is it not subjective? Because there is the history of Fallout and the developer quotes, where they even said that they could never imagine Fallout to be anyhing else than turn based and top down. The original developers said this. But that is not even the only point. But a very important one. The best thing you can do is to directly compare Fallout 1 and Fallout 3 and what you know about Fallout 4. And if you really want to be objective you have to get to the conclusion that Fallout 3 and 4 are not improvements to Fallout 1. That doesn't mean that you have to hate what Bethesda does. You can still enjoy all of the games for what they are.
Would you believe that changing Skyrim in to a Command and Conquer strategy game would be
objectively an improvement to the Skyrim game? Again, we are NOT talking here about taste or what ever.