We discussed this a few pages back....
Because they started the whole large mount is awesome thing and they had to carry on with it.
So they made larger lenses,
less sharp lenses, lenses that don't AF as fast, then a huge MF lens but that's not the end... to top it all off a APS-C body with almost no APS-C lenses and an old sensor (makes EOS-M look good) which I am sure will be the biggest benefactor of the large mount.
Then there is the crazy F mount stuff.
But they are all well corrected for CA
They should have just pushed to get the D6 out (which they are still working on!) And the second gen Z out. One of the best moves Sony did was refresh the first experimental A7 series as soon as they had some feedback even if it was with a year! Need to keep the momentum going.
Even canon have realised this. They got their sports body out and now they are focusing on RF.
The sad part is out all the mirrorless bodies the Z bodies are really ergonomically great. They really nailed that.