Summary:
Since a rather long time, ACRA seems to not attach logs to the crash report email.
For instance, I just got a crash and after the ACRA screen, Gmail opens on this screen:

As you can see, the email is empty, so there is no point sending it.
Fortunately I had logcat running this time, here it is, hopefully it can explain why the crash info is not included in the email:
empty_acra.txt