This Plugin adds the ability to change the vertical screen columns on the admin dashboard. To make a change to the amount of columns displayed click the screen options drop down and select the number of columns under screen layout.
Move to Plugin directory of the site and activate.
I didn't even realise the multi-column choice in dashboard had been removed until now when i started a new install (all my other websites already had it, installed before this change, so i had my 2 columns anyway). Really, wordpress devs, there's this pattern of removing simple, useful functionality -- why?
Now my admin screen is back to normal, thank you thank you.
Here is some good extra information:
(I wanted to reply to these, but "this topic is closed to new replies" -- well that puts a damper on the conversation, doesn't it?)
I totally agree with all the "complainers" there. If WordPress wants to optimise for responsive, that's great. So add it as a choice -- don't remove things. That's how you treat toddlers. We are not toddlers. We can handle choices and complexity, yes we can.