400 Tire Changes and those Oddly-Shaped Fenders

I did a "simulated" tire change in my driveway just to see how difficult it would be. Now I knew about the weirdly small fenders and foresaw how difficult it might be to change a tire but why are they like this? I'm assuming it's just a carryover part from the non-boondock model but why not make it match the 320 boondocks fenders and the diameter of the larger boondock wheel? It's not hard to get the tire back on but it's difficult to take it off. Just an observation.