Imagine the Hobson's Choice you just offered small-time artists. If you don't want to work with a large publisher, you either have to overvalue your copyright to the point of being buried by ruinsome, confiscatory taxes... or, if you don't want the taxes, then a large publisher can buy you out for pennies on the dollar. What that would mean is that you would lose the legal right to write your own work anymore.
Large publishers would benefit handsomely, as they'd be able to buy into a new market of hilariously undervalued work. You would turn every independent creative endeavor into the highly exploitative contracts that the average record label M&A lawyer writes on a day-to-day basis. Meanwhile, because these companies are already rich and powerful, they can just afford to pay the tax to overvalue their copyrights. So the end result would be a transfer of wealth from artists to publishers.
Furthermore, what happens to any existing licensing agreements? What happens if Microsoft buys out Linus Torvalds or the FSF with the intent of making Linux or GNU proprietary software? Does the GPL still hold, or does the buyout override the licensing agreement? The latter is bad for obvious reasons. The former would allow the use of improper transfers and creative accounting to partially evade the taxation regime. Hold your copyright personally, exclusively license it to an LLC on very generous terms, and then undervalue the copyright on your taxes. If someone does buy you out, they can't terminate the license for at least 35 years - upon which most of the copyright's value will have already been exploited.
What you seem to be asking for is a way to attack large companies for being large. The answer to your question is not to break copyright and patent law (more than it already has); but to actually enforce antitrust law, and reduce the scope and scale of copyright back to something reasonable.