It's because they term the Cisco or other Appliances as "Enterprise". These other ones have "no name" and as such they believe they do not meet "Enterprise" requirements.
2. The other reason is that these FreeBSD/OpenBSD types have got no certifications associated with them like CCXX, etc. They therefore cannot source expertise for these from the market place they way they do for MCXX, CCXX, etc.
The trick is "Enterprise". You find a way to stick that name to a device and you are in business. Else you are nameless and unknown.