Moreover, this could create a stronger incentive for miners to prioritize high-fee transactions over lower-fee ones, which can even lead to increased transaction fees and decreased network accessibility for smaller miners. These are more like flaws that exist in a decentralised system because even if power is relatively shared it can still be abused by people who hold huge amounts just like mining pools with tremendous hash rates.
Miners are already incentivised to prioritize higher fees over lower fees, that is by the design of the network. As it stands now, Bitcoin is already far less decentralized with 70% of the network centralized around 4 mining pools. They can always collude to artificially inflate the fees at any point in time, just that orphaning blocks is an entirely different ball game and the incentive would be drastically different. I read through the abstract and I can say a fixed rate might indeed be better to avoid this, although not disrupting the fact that an improved solution might even come before then.
I doubt that we would want to interfere with the free market forces in the fee market. There would be more problems created than solved in this case. It's quite difficult to incentivise miners to immediately broadcast whatever blocks that they have mined since the consensus function would have to be modified significantly. 
