I have no problem with the map sizes per se, I have however a problem with the fact, that the maps are full of glitches and problems because they are so large, that they couldn't be designed as thoroughly as they should be. So even with 1.10 there are misplaced textures and objects EVERYWHERE. You can't go for like 1 or 2 minutes in any given direction without seeing "hovering" trees, gaps in textures and so on.
There must be something serious wrong with your installation because the really fine thing is Witcher 3 is open world but has very few to almost none graphic bugs.
I really have a fine eye for glitches like for example hoovering trees and plants in thin air a meter above the ground, missing textures and other unnatural stuff like that when virtual wandering around in nature. I notice things like that on instant.
And I must say when riding around with Roach or walking around there are no graphics errors or glitches anywhere.
Far Cry 4 had indeed some hoovering misplaced trees, but Witcher 3 has no graphic glitches at all (except a wood cutter saw floating in mid air next to one of the Walls at Dandylions Club in Novigrad).
That`s the most impressive part - such a huge open world but still so fine and lovely hand-crafted graphics and no glitches visible.
Yes the woods in Witcher 2 for example around Flotsam looked better and more mysterious and fantasy-like because the trees were very much higher and gigantic and therefore more impressive with way more dense and gnarled branches and millions of leafes and all the trees were over 10 meters high with a closed tree canopy and you were unable to see the sky most of the time and therefore you really had the feeling of being "inside" a forest, and therefore the forests looked way more beautyful and mystical than Witcher 3.
Witcher 2 had these ancient looking Fantasy Movie or jungle-like sequoia like trees and Canadian flair. While Witcher 3 has more realistic and Central/Southern Europaen style small trees.
It`s a design difference of the vegetation style which made Witcher 2 look like more dense and impressive and wild and mysterious and jungle like while Witcher 3 has the common vegetation you see in nature when you look out of your window.
But the areas in Witcher 2 were so small and limited and Geralt always needed to follow narrow paths, everything was so small and it was no real exploration - that is the problem.
Witcher 2 Forests were reeeeally impressive, the trees seem to be 15-20 meters high with dense tree canopy and almost no sunlight on the ground just like in real forests:
https://www.youtube.com/watch?v=igJFh5nK0C8
Witcher 3 Forest doesn`t feel like a mysterious and fantasy-style jungle like dense forest anymore, it`s all small maybe 4-5 meter high trees with lots of space between them and no closed tree canopy and you always can see the sky. It beautyful and wonderful but the trees are too small and therefore it doesn`t feel the same, it`s not that fantasy-mysterious and atmospheric with fear of getting lost in a jungle-like fantasy Wallpaper forest who gives you the fear of the unknown:
https://www.youtube.com/watch?v=3d0rpytDxos
And that`s the only thing I don`t like in Witcher 3 and where I prefer Witcher 2, the design difference of the forests.
The whole open world in Witcher 3 is truly awesome and alive and beautyful, but I still miss these jungle-like fantasy feeling of W2 because the vegetation is not that big and impressive and mysterious and superdense anymore in W3.
But open world is way better than narrow paths and small levels because you can do whatever you want, explore whereever you want, and there is no need to follow waypoints and when trying to leave waypoints and make some exploration on your own you don`t always run into invisible walls and level limitations everywhere.
Open world is way better and offers the best gameplay possible - but the disadvantage is it can sometimes be a little bit generic-looking in some places.