Should tiling be a built-in option?
I can’t help with the design or programming aspects of your questions but I can give some input from the user side.
I would appreciate a strong set of intuitive key chords to manage windows size and position.
Let me explain:
I never gotten completely accustomed to a tiling window manager but I start to expect similar features form a conventional window manager.
From the user’s view tiling is noting more then the ability to be able to commandeer the size and position of windows precisely without having to fumble with the mouse. For example: focus window, press win+left puts the window on the left half of the screen followed by focusing a different window, press win+right puts this windows on the right half of the screen. This is very satisfying because of the gaps that are minimized/nonexistent or constant (i3-gaps).
Maybe a new class of windows manager - a snapping window manager?
By that I mean not an internal grid of tiles and sub grids but holes/space between windows that other windows can be send to and then snap into the maximally available space? With key bindings like win+left, win+right+up … to send them to the nearest empty space in that direction and win+alt+(arrow keys) to resize them combined with the snappy/stickiness of adjacent windows that resize/move there borders in concert? Maybe win+ctrl+(arrow keys) to move the focused window and have the others around it dynamically adjust to the pressure/vacuum the movement produces.
While writing this I remembered the first experience with the sticky and wobbly windows of Compiz.
I guess my proposal would produce the same oddly satisfying feeling while managing windows this way especially if the mouse could also be used and not just the arrow keys.
There is a magical emotional reaction of the brain to objects on screen that “behave” in a kind of physical way to your movement.