Not sure what is the drag and drop in this context? No drop involved.
I think most feelings on the discernability of the lines are that, as a seldom used function, they are discrete. But a change of theme might have some effect?
On my installation, if I select "size all columns to fit", it does, indeed, become the default.
But, as you are obviously very unhppy with the new look, I would suggest you try one of the third party applications. You may be lucky, but I have found, for the most part, that they individually have too many features, or features which are not required. I have invariably returned to Windows Explorer.