https://en.wikipedia.org/wiki/Silicon_Graphics#/media/File%3...
Rebranded in 1999, according to Wikipedia. I would think the old logo looked really bad on the web at the time, with monitors being 640 × 480 at 256 colors, if you were lucky. It also would have been expensive to reproduce well on letterhead, and I wouldn’t dare think of how that looked on photocopies (often monochrome at the time)
Now, could they have stylized/simplified the old logo and keep it nice? I wouldn’t know.