The main reason was to explain the special effects of some cereals and show their tags (since some synergies are based on tags, like golden/animal/chocolate...). Also, you are completely right, I should have written the base value of the cereal, since now the only to know it is to pick it up (they also are based on rarity). Never crossed my mind, so thanks for pointing it out!
Toys should have a tooltip explaining what they do both before you get them and after they spawn near your bowl, since you didn't see one I think it is a bug, I should check it out. As for the UI having the useless x1 quantity, it was a last minute change that cereals have a "persistent" state (some cereals getting new tags or accumulating value, like boats eating fishes and adding their value to themselves) and didn't have time to either find a way to group identical cereals or change the UI, since the game was made for the 7 days Brackeys jam.