@Christopher41, obviously I can’t speak for the KNIME team, but I know from discussions that they are working hard to make modern UI more efficient where (and when) they can.
I feel your pain though, especially when I have a table with a large number of columns.
A similar issue was raised re the Column Filter node:
Subsequently, (in KNIME 5.4, I think) “handles” were added to the dialog to allow expansion of the list boxes.
ie
I’m hopeful that this functionality is in the pipeline for all similar nodes, but I imagine that is a question of priorities in terms of when this happens, and I would still prefer the list boxes to be fully expanded to the available space from the outset, and that they expand/contract automatically with the dialog.
I feel these dialogs will probably feel somewhat better once they are being used in the Modern UI in “embedded dialog” mode (also introduced as an “experimental” feature in 5.4)…
source: https://www.knime.com/blog/whats-new-knime-analytics-platform-54
… but I do still share your reservations on the amount of space taken up/wasted, and you are right that in comparison to Classic UI, none of the dialogs are nearly so screen-real-estate-efficient - something I, and others, have fed back elsewhere especially with regard to data tables.
For now, whenever I want to do some “Column Resorting”, I prefer to use the Table Manipulator node over the Column Resorter node.
I have several reasons for this. Firstly Table Manipulator is still a “classic” config node 
, but additionally it not only lets you move the columns around, but also it lets you rename them, and you get a live preview of the output.
What’s not to like? I live in hope that such functionality will remain when it too moves to the Modern UI, as this is such a powerful node, but will have to wait and see.