I am familiar with the design. At the time, the only computers that were less timing dependent were the S-100 and CP/M boxes where you could swap out a CPU for a faster one if memory speed permitted.

I don't consider it a mistake - nobody at the time was realizing that we all would, eventually, move our software to faster computers every couple years. Woz is brilliant, but he couldn't have foreseen it and, as you point out, almost nobody did.