Even if SVR is measured for ITT, I think in real life there will be a portion of patients who will not be eligible (or will refuse to take) a regimen that contains ribavarin. So a company would be consciously limiting its market if it adds riba for a negligible bump in SVR rate.
It all comes down to a trade-off: if the benefit of adding riba is going from 80% to 85%, but the cost is a 25% chance of experiencing depression, what would you choose?