I also use the Command Editor (multi-line console) frequently to test code; if it disappeared that would be awful.
Coincidentally, just yesterday I noticed a limitation (?) of the Command Editor. I've been experimenting with adding a custom property to a function as a way to maintain state on a value; it seems much simpler and more elegant than creating a nested function (closure) or global var for that purpose. So I created a simple "counter" (add 1 to previous value) in the Command Editor to test the code -- and it didn't work. It just kept returning the initial value each time.
But then I pasted the same code into an HTML page, plus a link to click (to run the function multiple times), and the code worked fine: the counter kept incrementing by 1 each time as I intended.