Hi, imho in aoe3 was useful to have the main icon visible in the case you have some artillery units in your selection. In 99% of the cases you really don't care (can't care) about the HP of every soldier in your selection, but it's very important to have good visibility on the artillery HP. I think that this was the main reason which lead the developers to choose for that UI. I really appreciated that feature in aoe3, but i don't know if artillery (catapults?) will be so fundamental in 0ad (never played a real game actually).