A compelling discussion of my reasons won't fit in a comment. Perhaps I'll do a blog post in January.
If you want to know more before then feel free to email (in my profile).
I'll await the blog post; I can't be the only one who's interested the know the motivations. And for the record, I agree that it's the practical results that matter (for those who would criticize an OS choice). We're doing "embarrassing" things with what amounts to an EAV/graph database built on top of MySQL (with all the vertices in-memory), but we're incredibly happy with our results.