They might not fit in the game's old visual style, sure, but this is the new visual style that the game has been primarily using for over a year (started some time around 0.6.0 and 0.7.0).
I can understand liking the old style more, as I do like it's charm as well, but I can understand why they have gone for a more modern HL2-like style. They won't undo over a years worth of progress on the game because a subset of the fanbase doesn't like changes that have been generally well received by the rest of the fanbase.
119 days ago (+1)
There isn't really that much you need to know about the new visual style. Compared to the old one, it's mainly just higher resolution textures and more detail on textures and models.
As an example, here is the old MRE model (left) compared to the new one (right). Generally, the old style is more simplistic, while the new one focuses a bit more on detail.