Besides the facts that Sanddancer and thelibrarian already mentioned, I as a FreeBSD desktop user would like to answer the question in a different way.

> Why isn't FreeBSD suitable for a personal computer / desktop?

Next time you are visiting a BSDCon have a look around. What are the Systems FreeBSD devs are working with and what are the Systems OpenBSD devs are working with? It is not my intention to be polemic, but I think you will see that many FreeBSD devs (in contrast to many OpenBSD devs) are too pragmatic to use their own OS on their desktop and just use OS X.

At least that is my theory, why OpenBSD make a nicer desktop than FreeBSD -- as long as you don't need any FreeBSD features.