Chibnall has been quoted as saying that he only invited "Classic Era" Docs so as not to tread on what might be planned for the 60th Anniversary next year - read into that as you will.
On a more practical note, Matt Smith was probably too busy with House of the Dragon.
I thought it was brilliant.
The scenes with Ace and Tegan and their respective Doctors were brilliant, as of course was the totally unexpected multi-Doc scene.
Sacha Dhawan was superb too and, corny as it was, I loved the Ra-Ra-Rasputin scene.