The fact that they're not on the offense is not really meaningful. Most of the value of property and contractual rights is prospective. I bet Google has never sued someone for planting a farm on their campus lawn--that doesn't mean they're indifferent to the existence of that property right.
Google acquires a lot of companies for their IP. Not so they can sue people for infringing on it, but so they can use it. The property rights create a legal structure that allows those kinds of transactions to happen. Like with any other property right, that's the value of a patent--giving people a "thing" in which they can transact, which they can book as an asset, etc. Ideally, a lawsuit only happens when things go sideways.
Google acquires a lot of companies for their IP. Not so they can sue people for infringing on it, but so they can use it. The property rights create a legal structure that allows those kinds of transactions to happen. Like with any other property right, that's the value of a patent--giving people a "thing" in which they can transact, which they can book as an asset, etc. Ideally, a lawsuit only happens when things go sideways.