Sorry mate, but that's completely wrong. It's because when they're new, OE rubber lines have the same tensile strength as steel hoses, but are considerably cheaper than braided. It's just as time goes on they deteriorate, and braided don't - hence standard hoses being a 4 year service item!
The cost difference is a factor, but it is only a dollar or two per meter in commercial quantities, so no, it is not a big factor. It is not called tensile strength, but I know what you mean, but again, they are not the same when new. Unbraided hoses expand under internal pressure far more than braided ones, even when new, giving a softer feel. As they get older and the material weakens (from expanding) they expand even more to the point where braking force is comprimised, that is why they are a service item.
Having a softer feel means a rider is less likely to lock up when they snatch the brakes the way inexperienced (or unpracticed) riders are more likely to do, but it also means braking distance is increased because there is less rider control over the braking.
If you still believe braided and unbraided hoses are the same when new, ask yourself why most racers replace their new unbraided lines with braided ones.