Well the theory behind the tactic is that you can use a drop pod to land in a hot landing zone, the advantages of it being that its ALOT faster than a drop ship, can land places a drop ship cant, and is MUCH harder to shoot down. You use the drop pod to drop your troops in fast they hit the enemy hard and fast, taking out defenses and gun emplacments before the enemy has time to react, and the damage the do/territory they gain gives them room to bring in drop ships with heavyer weapons and supplys without the danger of having them shot down. It's not so much a one way trip as it is an express elevator. Where as a dropship would be good for landing conventonally, a drop pod is good for shock and awe/supprise attacks because the time from it's launch to the marines deployment on the ground is measured in seconds rather than minutes.