Is `dpkg-reconfigure --all` still available in 16.04?

After upgrading to 16.04, I tried to use that command, but it seems that dpkg-reconfigure (or dpkg --reconfigure) doesn't understand the option --all.

Is it still available? If not, is there an equivalent command?

Not equivalent, but probably what you are looking for if you want to be sure, everything is at least somehow configured:

dpkg --configure -a

You can try this script:

(
    for i in `dpkg -l | grep '^ii' | awk '{print $2}'`; do
        echo $i; sudo dpkg-reconfigure $i;
    done
) 2>&1 | tee dpkg-reconfigure.log

It reconfigures all installed packages and saves the log to dpkg-reconfigure.log file.