Because it doesn't seem "fair" to you? Gimme a break. They can either take it or leave it when it comes to an MFL clause. Plain and simple.
These are two large companies bargaining with each other at arms length. Hard for Samsung to argue like a consumer might that there is unequal bargaining power or that the term is a contract of adhesion.
The MFL clause only extends to financial advantages and disadvantages via an apples to apples royalty obligation. The only matters replaced are the rate setting clause for the licensed technology, not the covered technology clause.