Free market only works when everyone follows the same rules. When you have a player like China who is dead set on taking advantages of the rules but never taking the responsibility, you create an one-sided situation. Trade is not just an economic issue. It's a political issue when you have China in the game.
There's always a tension. Developed countries want as much access as possible for their advanced corporations to all markets around the world. They also want to be able to exploit cheap labor in developing countries without transferring any know-how to local competitors. Developing countries want to be able to export to the large markets in the developed world, but also want to protect their fledgling industries from much stronger competition from the advanced countries. They also want to acquire know-how from the developed world, in order to move up the value chain. Toyota probably wouldn't exist today if Japan hadn't protected it from American competition after WWII. This is why there are special provisions in the WTO for developing economies - the same policy doesn't fit countries in all stages of development.
Because of its uniqueness (both as the largest developing country in history and as a former non-market economy), China is actually subject to additional restrictions under the terms of its accession to the WTO. For example, other countries have increased leeway to place tariffs of Chinese goods, without China having the usual right to retaliate. It's not true that China is a particularly egregious rule-breaker.
I think that fundamentally, these claims of China breaking all the rules and taking advantage of everyone come from a place of fear that China will become the dominant world power - not from an actual understanding of Chinese economic policy.