It is unnecessary to buy them at huge cost.
The problems of these planes are-
They carry less amount of troops or supply than ships, very expensive, easy to shoot down meaning every thing on board will will be destroyed, can also crash.
Ships does not have these none problems. Modern technology can detect storm, soldiers and even equipment can be rescued from sinking ships. No fear of crash. Very hard to sink or to destroy. No one can carry anti ship missile unless he/she is superhero Hulk-:thumb:
To Transport Soldiers or weapons in case of future war fare Transport Ship is best. It can carry more troops and weapons than a plane and costs less. History proves it, these transport planes are only useful to send paratroopers(Operation Market Garden), drop supply for encircled troops(German Ju 52's in Stalingrad or US C 47's in Berlin air lift). To drop commandos or to supply weapons and troops to land locked countries, but when it comes to land locked countries even US tries to find a land route- US led multinational troops in landlocked Afghanistan and their supply route through Pakistan.
But today Helicopters can also do it.
So when we have to send large amount of troops and supplies, it is better to use Ships or to use ground route in case of land locked countries. To drop paratroopers or others less expensive and light transport plane is ok.
You can find in all major engagements when a country was fighting in far away from it's homeland, they used ships for transport. Even US.
To drop paratroopers it is better to use multiple light transport plane instead of few large transport plane. If enemy shoots down transport planes then whether large transport plane or small transport plane, all passengers will be killed.
So if a large plane carrying 120 troops is downed all will be killed, but if a light plane carrying 30 is shot down then only 30 will die and their will be still 3 planes carrying 90 soldiers, they can still achieve objective. I hope every one can understand it.
Money Rs. is always a deciding factor, so you cant use large planes in huge number as you can in light planes. And as I said if enemy shoots down a large plane all is destroyed but if they shoot down light plane, we still have many other planes to do.