Radical Technology introductions take time
When I think back to the history of flight and radical flight technology, it often takes many years to get it all sorted out, e.g., jet engines, helicopters, computer-driven flight controls, trans-supersonic flight, et cetera. It took years and many lives were lost along the way because pilots were willing to take the risk. Even the now reliable Harrier had its problems and it took years to sort out techniques to avoid hot-gas ingestion scenarios (one reason Lockheed beat out Boeing on the JSF).
While we are successfully using the Osprey as a truck, let's not forget that helicopters were used only in this way until the Vietnam War, 20 years after the first whirlybirds flew at the end of WWII.
The Marines want and need this technology because they need something that gets them deeper and faster into enemy territory. Having the speed and range of the Osprey lets them fly less obvious routes making it harder to defend any particular high value asset, or allows the Marines to insert troops at a place and time that the opponent has not prepared for.
The difference between then and now is the immediacy of media as every little flaw and major accident becomes fodder for media outlets to air the dirty laundry. Just look at your own headlines and your slogan, El Reg. We love to hear and read through all the hype and PR, but sometimes we need to step back and realize that there are real serious people out there letting it all hang out.