Well is it not cheaper(by payload mass) to have higher protection to your equipment than more fuel ? Any benefit is useful , and this could be substantial depending on the strength of materials used

I imagine that, mass for mass, it isn't (of the extra fuel you carry, each bit you expend means the rest has that much less mass to push). Also, I can't think of means of protection that would withstand a high velocity collision with space gravel, that wouldn't be at the same time prohibitively heavy.