"I never find myself wanting to use tmux for splitting up a terminal window when I'm already using a tiling window manager"
I don't want to launch extra terminal instances every time I want to split my terminal window. Also, there's no easy way to detach or reattach to separate terminals as there is to tmux. Nor is there an easy way to programmatically pass information to or from them while they are in the background or off-screen, etc.
That's not to say that separate terminal windows aren't useful. They are, and I sometimes use them myself (particularly for drop-down terminals like guake or terminals in i3's scratchpad).
I don't want to launch extra terminal instances every time I want to split my terminal window. Also, there's no easy way to detach or reattach to separate terminals as there is to tmux. Nor is there an easy way to programmatically pass information to or from them while they are in the background or off-screen, etc.
That's not to say that separate terminal windows aren't useful. They are, and I sometimes use them myself (particularly for drop-down terminals like guake or terminals in i3's scratchpad).