But that ability makes no sense because you won't build your immobile 17pdr behind a shoot-blocker to only use this ability from then on for 60mu each time you use it. You'll always build it with open shooting field
There's not a single point on any map with 80 range of open space in all directions. You usually build a 17 pounder in a spot that has plenty of direct LOS, but there are plenty of cases where the world piercing shots ability can come in handy because the enemy is on one of the flanks or whatever, behind shot blockers. Most maps are designed to have big shot/sight blockers to divide up the open spaces specifically to limit the effectiveness of long range direct LOS weapons, where world piercing can give you an advantage every now and then.