Depends for what you need GUI. You need it for complex LOB app? So no, editor will be good.

Personally, i write c# and xaml, and i dont use the editor (vs or blend), but i edit directly the xaml.

About f# and gui, depends on use case. For example https://fslab.org/XPlot/ to show graphs.

  let series = [ "bars"; "bars"; "bars"; "lines" ]
  let inputs = [ Bolivia; Ecuador; Madagascar; Average ]
  
  inputs
  |> Chart.Combo
  |> Chart.WithOptions 
       (Options(title = "Coffee Production", series = 
          [| for typ in series -> Series(typ) |]))
  |> Chart.WithLabels 
       ["Bolivia"; "Ecuador"; "Madagascar"; "Average"]
  |> Chart.WithLegend true
  |> Chart.WithSize (600, 250)

this is used to generate programmatically i chart. inside a window with some layout, usually in enough. And i can do testing in the repl.

But yes, if you use editor like c# version, F# is less nice to use. But again, programmatically allow other things, like https://github.com/fsprojects/Elmish.XamarinForms

So depends how much time you edit the view (and why), vs gains in the logic behind the view. For me the global tradeoff, but depends, so you are right.

The only time I have ever felt compelled to design a UI visually is when working with iOS or macOS because the framework is so centered around Interface Builder. When I write a WPF or JavaFX view I am not using Blend/Scene Builder to drag and drop controls, but to have a mostly-accurate preview of what crap looks like without having to build and run.

Yes, it keeps trying to reach parity with native UI design tooling both on desktop and mobile OS.