Once upon the time most patents were filed with the hope that they will be a source of revenue through royalties.
Now most patents are filed by companies who own the patents of their employees with the purpose of being weapons against competitors. The patents are used either to prevent the appearance of new competitors or to ensure that the existing competitors cannot push the patent owner out of the market.
When the purpose of the patents is anticompetitive, the patent owner either refuses licensing or requests absurd conditions for licensing, knowing that nobody will be able to accept those.
I agree that what you propose would be a great improvement in the patent law, restoring the original purpose of the patents, of being only a source of revenue, instead of preventing any competition.
Moreover, there are very few examples, if any, in the history of patents, when a patent, especially a revolutionary one, was enough for making useful products, in the form conceived by the inventor. Almost always, the patents became really useful only after others have invented additional improvements, removing various shortcomings of the original patent.
When the patent owners refuse licensing, even if they are not patent trolls and they really attempt to manufacture products based on their patent, they typically do not succeed to make products as good as those that would be made by a third party who would have licensed the patent and then would have added improvements on top of it.