The V-22: Too Much and Not Enough: Anyone going into combat has a "too much ain't enough" attitude towards their weapons and equipment. It's a matter of life or death. In wartime you quickly discover which new item works, or don't. In peacetime you have to guess, and that can get pretty expensive. When there isn't a war going on, you have no easy way to get rid of expensive mistakes. You end up with a lot of gold plated turkeys. This is part of the case being made against the V-22 Osprey aircraft. 
The V-22 project is over twenty years old. In the early 1980s, the V-22 got the green light, and the first of many billions was set aside for R&D. It's advantages were obvious. The two engine Osprey has wings that rotate, allowing it to land and take off like a helicopter, but also move faster like an airplane. The V-22 can carry 24 troops 400 kilometers at a speed of a speed of 700 kilometers an hour. Because the V-22 can perform like a fixed wing aircraft, it can more readily move itself thousands of miles, on short notice, to far off hot spots. This ability to "redeploy" across oceans is always attractive to the United States, for we have to cross an ocean to get to any battlefield. 

Currently, and for some thirty years, the CH-46 and CH-53 helicopters were the only aircraft available for moving Marines long distances over the battlefield. But the CH-46 can only carry a dozen troops for 150 kilometers at a speed of 300 kilometers an hour. In moving heavy equipment the V-22 also has an edge, for the V-22 can carry a five ton load on a sling for 150 kilometers while the CH-46 can only move 1.5 tons for 100 kilometers. 
There are two catches, however. The V-22 costs much more than the helicopters it replaces, and the V-22 is a much more difficult aircraft to maintain and keep operational. Already, the testing has led to three crashes and 26 dead. Depending on how many V-22s are manufactured, each one will cost from $60 million to (more likely) more than twice that amount. This more than four times the cost of the CH-46. But the 1960s era CH-46 is not made any more. There are two possible replacements for the CH-46. The low cost one is the CH-60 (navalized version of the Army's UH-60 Blackhawk.) This chopper costs about $15 million each, but it is much less capable than the V-22, with a cruise speed of 250 kilometers an hour, carries only a dozen troops and half the range of the V-22. The higher cost replacement (at $30 million each) is the CH-53. This helicopter exceeds the V-22's capabilities in some respects. It can carry more troops (up to 55), lift more sling weight (18 tons) and has the nearly the same range. But it is slower than the V-22, with a cruise speed of some 260 kilometers an hour.

So it comes down to speed. How much is three times as much speed worth? When moving over enemy territory, speed can be a life saver. The V-22 can come in fast and low, making radar detection difficult and moving too fast for ground troops get a good shot at them. If there were a war going on, we would find out real quick just how much the speed was worth. But in peacetime you have to, well, sort of guess. The V-22s proponents are guessing that speed will save lives, the opponents are not so sure. 

Meanwhile, the existing CH-46s and CH-53s need to be rebuilt before they fall apart. The Marines are betting their future on the V-22, as money is tight and cash for refurbishing their helicopters is going to build V-22s. This isn't all the Marines doing, the Navy is ultimately in charge. The admirals, since the end of the cold war, have seen fast moving Marines as a way to get a larger chunk of the defense budget. The V-22 can move Marines from carriers offshore to hotspots faster than anyone else, thereby grabbing headlines and the attention of Congress when budget time rolls around. This sprt pf thing appeals to the publicity savvy Marines as well. But the cold war saw everyone's budgets cut, so the army, which was originally were going to buy most of V-22s have pulled out. Currently, the Marines will buy 360 Ospreys, the Navy 48 (for hunting subs and making deliveries to carriers) and the Air Force 50 (for rescuing pilots and delivering commandos. This is why each V-22 will cost over $100 million. 

Didn't anyone see this coming? Sure, and everyone involved looked out for their own interests. Once a major procurement project gets into the defense budgets, promises are made and must be kept. The manufacturers make sure that parts of the new system are made in as many Congressional districts as possible, thus creating reelection pain if the project is cancelled. When it comes to that, not general or admiral is going to risk the wrath of Congress by saying things like, "no sir, we don't need it and we can't afford it."
It's politics, son.