I would like to have an option to not see "Popular Collections". I feel it takes the focus away from new mods. I have never used collections before and have no intention to ever do so, that's not to say they're a bad thing, I just don't want to see them.
I agree with the assertion that there is too much wasted space. The game title header takes up way too much space, I'd prefer if it wasn't even there. There is too much vertical space between sections (Trending Mods, Popular Collections, More Mods). It would also be nice if the page automatically expanded horizontally to fit the browser's width, allowing more mods to be shown in the "More Mods" section.
Visually, I dislike the new color scheme and how the game's icon determines the background color for pages. The new mod page colors feel harder to read text on.
EDIT: The new NEXT mods section UI is wonderful, it feels much more intuitive to search for and see mods.