Atari claimed the 68k in the Jag was only there for reading controllers but if that were true, then why would you "experiment" with making prototype versions using far more expensive 68020 and 68030 processors? I guess to read the controllers faster because that makes sense.
I honestly think that the Jaguar should have slightly less streamlined architecture, with a 68010 for the CPU, if not a 68020, and a more robust Jerry chip/processor.