Why switch to fcitx5

The README does not explain at all, only that it's the next generation. I had no issue with fcitx4, and I don't care that fcitx4 in maintenance mode. Why should I switch?

After trying for a little bit, this is why:

Unless something breaks spectacularly, I'm probably not switching again for some time.

Aside: making fcitx.el work for fcitx5

fcitx.el is an Emacs package that automatically disables the input method when entering contexts that only really ever expects English input. For example, it disables the IME when leaving insert state, allowing normal state commands to go through.

It works out of the box for fcitx 4; for fcitx5, this will make it work:

(setq fcitx-use-dbus nil ; fcitx.el doesn't know fcitx5's new dbus interface
      ;; the command name changed, but the switches and arguments haven't
      fcitx-remote-command "fcitx5-remote")
(fcitx-default-setup)