We needed (and still need) to teach (some) Torah to girls as a Hora’as Sha’ah.
When we restore slavery (if this transpires before we regain full strength), we may need the same Takanah for slaves, as well (with certain safeguards, same as with girls).
Kesubos 28a: דאמר ר’ יהושע בן לוי אסור לאדם שילמד את עבדו תורה.
As it is, עבדא בהפקירא ניחא ליה…