Because they haven't figured out how to have Axe-Edit add new parameters to its interface automagically. How do you get a program to add knobs and buttons to its interface by itself? Have you ever seen software that does that? How does it decide where it should put those interface items and how they should look and what they should control and have that go bugfree? If you know, please tell Fractal.
Software has to be adapted for new parameters. It does pull new definitions of the parameters it already knows from the AxeFx, like new models of amps and effects. That's a pretty big leap already. But knobs that weren't there before? That's way hard.
I do think it's taking them a while to get the 12.03 parameters out. It used to be inside of a week to get a new AE. Possibly it's quite a job to incorporate the new parameters. Possibly they're waiting for something else to drop so they don't have to release new EA's every week... And with Cliff on a roll like now...
Maybe Axe-Manage is almost ready?..
So. As someone said: New parameters will indeed not be in Axe Edit until Fractal releases an updated version of it.