D to D,
May be its a legal thing. A bit like you can have a single engine failure but only loss of thrust on both engines.
To admit that your product is fallible might invite product liability etc. The LGTU is in place to retract the gear in a SE case enabling the a/c to meet and exceed the min climb gradient for certification for individual and fleet wide aircraft. A bit like the remote vs unlikely case-they both have a % odds probability which we as pilots and passangers have accepted as safe-which it is.