Compare Leviticus 21:17 and 24:
דַּבֵּ֥ר אֶֽל־אַהֲרֹ֖ן לֵאמֹ֑ר אִ֣ישׁ מִֽזַּרְעֲךָ֞ לְדֹרֹתָ֗ם אֲשֶׁ֨ר יִהְיֶ֥ה בוֹ֙ מ֔וּם לֹ֣א יִקְרַ֔ב לְהַקְרִ֖יב לֶ֥חֶם אֱלֹהָֽיו׃
Speak unto Aaron, saying: Whosoever he be of thy seed throughout their generations that hath a blemish, let him not approach to offer the bread of his God.
וַיְדַבֵּ֣ר מֹשֶׁ֔ה אֶֽל־אַהֲרֹ֖ן וְאֶל־בָּנָ֑יו וְאֶֽל־כָּל־בְּנֵ֖י יִשְׂרָאֵֽל׃
So Moses spoke unto Aaron, and to his sons, and unto all the children of Israel.
Rash"i, Ib'n Ezra and others explain why Moses spoke to B'nai Isra'el as well, even though that wasn't explicitly stated in the commandment in v. 17. I understand that, and I assume that since the commandment was mainly for Aharon and Kohanim, Aharon's sons needed to know, as well.
My question is, that if these two other groups of people were to know these laws, why didn't G-d explicitly include them in verse 17?