I am aware that the rotation eliminates all cards/blocks older than Kaladesh. However, I have the Kaladesh deck builder's toolkit, and I remember that the toolkit included boosters from pre-Kaladesh sets. To quote a review from Amazon.com: https://www.amazon.com/Magic-Gathering-Kaladesh-Builders-Toolkit/dp/B01LDESLBG/ref=sr_1_1?ie=UTF8&qid=1506446358&sr=8-1
"Bought this for a present. They got a few good cards out of it. Came with 2 packs of Kaladesh, 1 pack of Eldritch Moon and 1 pack of Shadows over Innistrad. The other packs had some decent cards as well."
So how are we excluding cards that were included in a Kaladesh product??
I am not sure of the concern. The Kaladesh Deck Builder Toolkit wouldn't be much of a Toolkit if it only included Kaladesh cards. You won't often see standard decks that are limited to one set/block, so the Toolkit gives you a way to build with a larger pool of cards.
Yes, it might suck to pick up a Toolkit and get packs of cards that aren't legal. But, I would think most people would just get the Ixalan Toolkit when it gets released.
https://www.amazon.com/Magic-Gathering-Kaladesh-Builders-Toolkit/dp/B01LDESLBG/ref=sr_1_1?ie=UTF8&qid=1506446358&sr=8-1
"Bought this for a present. They got a few good cards out of it. Came with 2 packs of Kaladesh, 1 pack of Eldritch Moon and 1 pack of Shadows over Innistrad. The other packs had some decent cards as well."
So how are we excluding cards that were included in a Kaladesh product??
Yes, it might suck to pick up a Toolkit and get packs of cards that aren't legal. But, I would think most people would just get the Ixalan Toolkit when it gets released.