I think not being able to tunnel captures makes backline capping literally impossible on some maps, so I think a nice middleground after the haul PR would be to add 2 or 3 static “large” tunnels, that are invincible but always in the same spot, to make a high risk high reward avenue for capping. If marines dont guard them or otherwise set traps, backliners will be free to tunnel back to hive with their haul.
If the tunnel is immune, you can tunnel to it and not be at risk of dying if it is guarded. It can have a max of 1 or 2 bugs inside it so it doesn’t become a fob siege tool
As @DaTimeSmog Said, the reason it’s a thing is a sort of counter measure to double burst. But besides that, I kind of like cap’s not being a complete guarantee. To have a chance, all be it a small one, to potentially escape from a lurker or runner who capped you in some fair off place is a good thing. It allows for more interaction from both players.