I think there should be more indications that your units are hitting the ground. We obviously learn to spacebar-survey the ground, but I still sometimes miss it and noobs are hit by it much more.
- Direct fire weapons shoot up high but thin dust plumes whenever they hit the ground.
- Splash, indirect fire and beam weapons don't.
- Plume is proportional to damage, capped to 100% size at T2 PD level (~70 damage).