No one would be getting paid (by way of tax discount) for a patent unless they're already doing something the market values and therefore generating an income to tax in the first place. It doesn't matter if the income is from use of the idea in the patents or not. Any income generation is a sign the market is rewarding them for something. The government doesn't need to decide anything differently than they do now.

The patent system is already flooded with useless and novel things. The reason is that people are hoping that over the next 20 years (or whatever) that the idea might suddenly become valuable and they can profit off it. With my idea, at least, you cannot profit from a patent unless you're already profiting in the market.