I'd rather keep this discussion out of here, being a Catholic and all--but, it's good they didn't make all characters homosexualable.
Why?
In any work of fictional literature, it is imperative that characters be consistent and believable. Insofar as homosexual relationships are simply not the norm, statistically or socially, in this world OR (more importantly, by far) in the Fire Emblem world, it is healthy in the maintenance of immersion to keep their level of representation reflective of that. Characters would be shallower, and largely inconsistent with their world and many player's expectations. Additionally, it could be seen as the writer using their platform as a very blatant soap box, the same exact problem Ayn Rand's books had, thus cheapening the experience further and making the characters even more shallow.
This is something I don't think Kibayashi-san would do. Furthermore, it'd hurt him as a professional.
Now, I'm not saying any piece of fictional literature that subverts norms is bad, not at all, what I'm saying is that any blatant and shallow subversion of said cornerstone and integral norms makes poor quality art (and, thankfully, poor sales due to the often controversial nature of the change). Fates, on the other hand, is subtle, and does not cheapen the experience, this is due to the low volume of its subversion of series norms.
AH THERE IS NO ANNA IN THIS POST
QUICK, UH, UH...
I'm sure glad Anna was kept in her pure waifu-material (imhoooooo) form!
Also I stayed up 'til 4 in Trihex's Twitch chat and made my waifu for the waifu-bot Anna, and got an up-rating instantly from another Anna fan there. :D
Edit: also discovered that I have more power than 99% of Twitch chat users thanks to a staff member.