Do you play more than 6 virus cards? Are you in the anarch faction? Then you should only ask the question : why do I not play Cookbook?
The value is great! With Botulus, it allow you to break most ices on the same turn you install it. With Fermenter, you get 2 more, paying for itself. With Imp, you can trash a third card, getting more value (especially for René "Loup" Arcemont: Party Animal).
At 3 influences, you must have a very specific deck to justify using Cookbook out of faction.
Like most support card, there is few reason to have 3 of them in a deck, unless getting it early is part of the win con of your deck.
Great art, great flavor, great effect, great card.