Was a "planned weakness in the Death Star" story really necessary?
There's been a lot of criticism over the years about how the Death Star had a very stupid design flaw, and so to solve this, they made Rogue One to explain that away (and to make money). But seriously though. lets just think about this so-called flaw/trap.
A small one-man fighter needs to travel miles down a trench (considering the traffic beam is turned off), while guns shoot at them and enemy fighters likely attack them, then fire a proton torpedo into a tiny hole only 3 meters, somehow making a shot that causes the missiles to curve 90 degrees, and then have them travel literally miles in a perfectly straight line down a narrow shaft while exhaust is pouring out (which should push the missiles away, or even into the wall), and then hit the main reactor.
Ok, seriously, what kind of "trap" is that? The target is like impossible to hit UNLESS you're a Jedi, and even then, come on. Was there really an explanation needed? This so-called trap is so astronomically impossible that making it a "flaw" in the design actually makes more sense than Jyn's father putting this impossible to exploit weakness.
For a funny video of this, click the following link: https://www.youtube.com/watch?v=agcRwGDKulw