It's an option but I guess then you as Organiser have to satisfy yourself (and ultimately AUK) that your riders are indeed following the prescribed route. I think at the very least you would need to add an advice to the top of the routesheet:
YOU SHOULD FOLLOW THIS ROUTE AS CLOSELY AS POSSIBLEor some such, possibly worded more strongly. Of course it helps if you have a bullet-proof route (unusual these days, when there is so much avoidance of main roads) and if you don't, you might want to mount a secret control. Or some other means of checking, such as GPS tracklog inspection. All sounds too much? Hence endless strings of ghastly Info controls.
As far as I’m aware the Organisers handbook is silent on whether the distances shown on the Brevet represent the official route or shortest distance. Ideally they would be the same but they never are. As is, the control times published in the Brevet are derived from the registered control distances.
I’ve always taken the view the Brevet distances should match the official routesheet as it what most riders would expect though technically perhaps they should show the actual shortest allowed, but then showing different distances in the brevet and routesheet inevitably generates further confusion and debate, all of which acts to undermine AUK Events and Event Organisers.
You'd need an online route sheet generator (similar to the way Google Maps, RWGPS etc generate route instructions) obviously tailored to cyclists' idiosyncrasies, which would then drive the intermediate distances on the brevet card, which in turn drives the opening and closing times**. Although the standardisation would be welcome in some ways, I think we'd lose more than we gain, because I always found the differing route sheet styles to be part of the pleasure of audaxing.
** as you say, you enter the distance and the times are generated - though I suspect some organisers don't notice that it is possible to edit these times if you don't want them slavishly following the distance. For example if your first control is a cafe 40km down the road, and you know it doesn't open until 09:30, then it's pointless really to have the control box opening at 09:20, and much neater to edit it in the Planner rather than altering the time with a pen on each card as I have often seen done.