The Air Force and Navy are both wedded to an outmoded industrial age view of warfare in which machine fights machine and the best machine wins. We are the best in the world at that type of warfare. However, our enemies don't fight that way. Our national military strategy is beginning to take the people-centric, land oriented nature of warfare into account. Resources should follow, but there is huge resistance from those wedded to the machine model--i.e. Admirals, Air Force Generals, many in Congress, and of course the defense industry.
The point is we cannot afford to build an entire fleet of designed from scratch tactical airlifters.
Also, airlift can NEVER carry significant amounts of Army equipment - it must travel by land or sea because no planes in the world - including C-5s - can haul enough to move a division (or even brigade) of Army equipment in a timely manner. Infantry, yes - but if it has wheels or tracks, it just weighs too much to fly.
There is a reason Ford doesn't distribute their cars to dealerships by air...
The point is that Air Force transports exist to support the fight.
Not according to the AF Brass. According to them the AF can do it all.
(note I'm ex AF)
This is an old story, of interservice rivalry. It's not a problem at the pointy end of the spear, but in the pentagon, if your in the Navy your worst enemy is the Army, and (of course) both gang up on the AF, the Marine, they'er left sucking hindtit. Of course this all changes depending on who's on top, and who's ox is being gored.