That's pretty much the only reason anyone bought an SGI workstation over most of the company's first incarnation as well. For some reason they were forced into using Irix, so they had to buy one.

That's not my understanding at all! SGI had state of the art graphics (and other A/V hardware) at the beginning. At the end of the workstation market, commodity hardware got to the "good enough" level for a lot of people. A number of SGI engineers went to Nvidia.

At the end of SGI's first life, PC hardware was running rings around Irix workstations. The O2 was basically the slowest machine you could buy at the time. Where I was working at the time we switched our PRO/Engineer machines from SGI to whitebox PCs as soon as PTC ported to Windows NT. A dual-CPU Pentium Pro with Fire GL Pro absolutely smoked the O2 and Indy machines it replaced. So that was my experience, a shop that bought SGIs as long as they were the best platform for a particular software package, and threw them out at the earliest opportunity.

Imagine if it ran IRIX...