I'm a big fan of Jean-Louis Gassée and I wish there were more visionaries like him in the personal computing industry. He helped push the Mac further during his tenure at Apple, and his work at BeOS also pushed the state of the art of personal computing. There are two major standouts in his career that I greatly appreciate: 1. His transformation of the Mac from the non-expandable appliance it was in the original 1984…
Don't quote me on this but the another powerful feature was the decoupling of media codecs from programs. Adding support for a new media codec was as simple as dropping a .so lib file into a /lib/codec directory and all your media programs now supported that codec. This applied to all media including audio, video and images. This was all part of the BeOS API.
It also had a decent c++ API and multithreading was a first class concept in the system allowing one to easily write programs to take advantage of multiple processors. That allowed the machine to easily scale as you added more processors, something Windows 98 couldn't do at the time. This was well before the concept of multi-core. Back then you needed more sockets to add more processors and it wasn't cheap.