Half an operating system: The triumph and tragedy of OS/2 | Ars Technica.
The trouble was that GUIs took a while to develop, and they took up more resources than their non-GUI counterparts. In a world where most 286 clones came with only 1MB RAM standard, this was going to pose a problem. Some GUIs, like the Workbench that ran on the highly advanced Amiga OS, could squeeze into a small amount of RAM, but AmigaOS was designed by a tiny group of crazy geniuses. OS/2 was being designed by a giant IBM committee. The end result was never going to be pretty.
If you've never worked with IBM, this single paragraph will tell you all you ever need to know.