It's because you pay attention most when things go out of plan. When you spawn right next to the flag you brush it off and don't pay attention but when the spawn points screw up your plan then you take notice.
Well... Firefall had a reason for that. In their lore many of the things before and during the Firefall were lost or destroyed which meant that having soemthing from one source would be somewhat conspicuous.
For Legions we have nothing except it's former name. Fallen Empire Legions. Which could...
There was a HUD in the old forums that someone had posted that had basically the same premise. It removed most everything except for small bars at the top and bottom of your screen.
I think it was called Immersion.