In my limited understanding it seems like armour is usually too heavy to be used, or too light to be useful. And in aircraft the problem is many times worse than usual.
I think Draconis has it right, the solution is along the lines of:
- Get rid of the parachute altogether, it is the absolute worst, last-resort option for getting troops down if you can’t land any kind of airframe at all
- Improve the gliders to get the troops down on the ground as fast as possible, with the least possible risk of injury on landing
And then build good tactical transports so you can start flying in and out as soon as any kind of flyable spot can be secured.
Where I do think you are correct is in identifying that the cost of losing a decent number of highly trained troops, plus also potentially losing the battle due to casualties, makes it worthwhile to invest a decent chunk of money in getting them down safely.
All that pissing about with cheaply-built allegedly-reusable deathtrap gliders which happened OTL seems to me the epitome of ‘penny wise pound foolish’.