RAD isn't really relevant anymore, but it was very handy on a floppy-based system without a hard drive.

Data types, on the other hand, were absolutely amazing. Sure, ffmpeg covers some of it, but datatype support was, and remain, a killer feature of AmigaOS. Want almost universal support for a new format, including support by legacy applications? Datatypes. Want to replace a common format's encoder with somerhing else? Datatypes.

The other killer feature of AmigaOS applications was the AREXX support, which allowed advanced scripting far before it was available on other consumer platforms.