The time-limited monopoly is part of the deal, yes, but the ultimate goal is to prevent invention from being kept secret. The monopoly is granted specifically i

The time-limited monopoly is part of the deal, yes, but the ultimate goal is to prevent invention from being kept secret. The monopoly is granted specifically in return for the (eventual) public availability of the invention. The reason behind the restrictions (obviousness, the existence of prior art, etc.) is that no public good can be obtained in exchange for the monopoly award. Somewhere along the line, the idea that patents are meant to serve the public good seems to have gotten lost...