One other example is RAID. Why should I have to know or care exactly what brand of RAID controller I have and what driver that particular RAID controller is using, just to be able to refer to the array? For example, in FreeBSD:
"/dev/aacd" is used to refer to an Adaptec RAID device,
"/dev/mlxd" or maybe /dev/mlyd for Mylex RAID,
"/dev/amrd" for AMI RAID,
"/dev/idad" for Compaq Smart RAID,
"/dev/twed" for 3ware RAID.
And after that, you need to add the other information to refer to a specific partition:
"/dev/twed1s2e" (or something like that). Now that is an intuitive and obvious name.