Well, it would be simpler for the programmers, but that's not the point. Real Plan is supposed to plan it all for you/us. Sure, we're supposed to make sure everything is correct, but I agree. If you're going to build something like this it should have all the bells and whistles possible. If I were the designer/programmer, I'd like to think I'd regard this as a bug/omission in my code/product.
I'd say that IF we ever get real time weather displayed via ADSB, and you're on a Real Plan, I'd like to see it suggest deviations around storms, icing, turbulence, etc. But I suppose we've got a long wait for such things.