When using the side panel for thumbnails, clicking anywhere on the thumbnail is like a soft select, you have to click the little box or else if you scroll the document your selection disappears. if you select anywhere else on the thumbnail, it's also very difficult to see what is selected.

Then when you drag the selection to extract, it unselects the page you dragged it from so when you want to delete the selected pages after you extracted them, that page is left hanging around.

You should be able to select the thumbnail like in the old adobe, by clicking anywhere on the thumbnail. And after dragging it out to extract you should be able to just delete the entire selection.

Lastly, in order to rearrange pages, you have to select the little thumbnail box instead of being able to just grab and move the selected thumbnail. Very time-consuming for rearranging pages.