One thing that Titanfall alpha testers noticed is that you cannot shoot through walls in the game. This is very unlike Call of Duty or Battlefield which allow you to shoot through sufficiently flimsy structures in order to damage your opponent. Heck, both titles also fool around with destructible terrain, actually allowing your cover to get blown up if it takes enough damage. But that is not the case with Titanfall . Why? Game Balance.
A Titanfall developer going by the name “scripticaus” explained this rationale on the game’s official formus. The problem is that it would make Titan weapons too powerful. Titans, the giant robots of the game, fire huge cannons and immense chain guns that can easily tear footsoldiers apart. If these weapons were able to shoot through walls or destroy terrain, Titans could basically spray and pray and hope that they hit something. One of the advantage of pilots outside of their mech is that they can hide in crevices and in buildings. It wouldn’t make much sense for robots to be able to shoot right through the main advantage that pilots have.
“Another title having a feature is not the bar by which we justify features,” scriptacus said. “While I’m acutely aware of the benefits of bullet penetration in the tactical shooter genre, with the way this game plays I’m not sure what sort of design space it would really open up. It’s certainly not a feature I find myself missing and I don’t even think it qualifies as ‘something we would definitely have done if we had the time.’ No doubt we’ll evaluate it further depending on our next project, but it’s definitely not a no brainer.”
Source: Titanfall Formus