Because I already got burned once paying for TextMate and having the development basically die. The same pattern seems to be happening with Sublime Text.
So I finally just started using Emacs instead. Setup my keybindings so they're Mac/Sublime Text like and wrote a little custom frame/window manager in elisp to make the application behave the way I want, and I'm free from having to worry about one of my core tools turning into abandonware.