[Imp]

On the original question air mobile have there uses but only if the situation allows or warrants it due to there high cost.
Good masking terrain drop off as far forward as possible, you now have 2 choices continue on foot or act as scouting parties so main force can move in relative safety, losses its effectivness unless main force is fairy mobile to. They can then fall back mount back up & become a reserve to go in once AA is at an acceptable level.
Several hills to drop them off behind would be an example perhaps not on the best viewing spots as they could be pre plotted for arty.
The other use is more high risk & will incur losses so its a case of will the loses gain me time & prevent other losses. Going for chokepoints might be worth it, things like a river crossing control of the other bank or an idea of whats defending it can be worth the casulties. Timing is the key thing they will not survive on there own they are a distraction to let the main force cross in relative safety. Again several options trying for direct control of the riverbank could be very high risk but landing further back means his reserves are chasing them instead of moving to cover the crossing.
There main use though is as a fast response team once the enemy is already engaged cutting of routes for reinforcement & or route allowing for quick destruction of the enemy so you can hopefully get out of there before the arty turns up, encirclement in a nutshell.
But its always a high risk op hence there needs to be a reason to commit them, just like Paras there will be losses.