Once Apple replaced all the original ///'s with fixed machines, they became very competent, with excellent software, and usable hardware. Unfortunately, the rep that was left from the original machine was never overcome. And yes, design decisions by Steve Jobs (specifically no fan) were the root cause of the biggest problem the machine suffered, loosening of the socketed chips.
As a point of fact, the original Apple /// was withdrawn from the market and replaced with a model that fixed the initial problems. All of the original purchasers had their machines replaced free, and the machine was manufactured for 2 or 3 years and accomplished its original goal. I owned 3 of them at one time, with Profile hard drives; I am aware of many others that were in use until the Mac took over the market. They ran Apple II software well, and their own software, particular the precursor to Appleworks, was quite usable.
May 19, 1980: Apple III. Worst. Apple. Ever.
Five Biggest Apple Mistakes