It sounds like the people asking for this don't know how game development works. The world in 1.0 was big and empty and repetitive. It had to be in order for it to be that big. Because there can only be so much stuff loaded into memory at one time they have to repeat things a lot, like grass texture and dirt texture and rock texture can all be vertex painted onto the surfaces and blended in any way they want so it looks different then another part of the area but it is only 3 textures. The same is true for every single thing you see in a zone if you look hard enough you will find a tree or 5 with the exact same geometry, it's just rotated and placed in ways that you don't notice it.

In 1.0 the world was exactly the same but because it was so big there was the same amount of stuff loaded into memory but spread out over a much bigger area and it was a lot more noticeable that things were repeated and empty. When a map is smaller you have much less space to fill with the repeated textures and geometry so you can have more set piece geometry and textures (things that stand out and don't need to be repeated). This hasn't changed from 1.0 - 2.0 and till now. There's still a memory limit and no matter what making the maps bigger will make the repeated assets be much more noticeable. Even in the sea of clouds and other areas it's more noticeable that the textures are repeated on every tree and the ground when you fly high enough.

If you didn't know when 2.0 was being developed, they ditched the big empty zones in favor of smaller more interesting zones. The community agreed and so did I. Now you may be thinking that this has nothing to do with loading screens being seamless but it is the entire reason they are not seamless currently and they won't be unless they completely remake all the maps. If they remove a zone then the game has to load all the memory of things on both sides of that zone and that's usually not possible because there are new textures and models that exist in one zone and not the other.

This will be a problem either way, unless they raise the minimum memory limit to favor only higher end pc users will they be able to add more models and textures but they won't do that because that will limit the playerbase more. But even if they did there will always be a memory limit and they still need to choose if they are gonna have big repeated areas or small set piece areas. And they already decided that along time ago.