I think the answer is pretty straightforward. Susan's is clearly a place for transpeople, and most SOs are seeking out support and information in forums where there are not trans folks reading their posts. Remember that SOs need to learn a lot and adjust a lot to the revelation that their partners/spouses are trans...and just what that means for their relationships and their own identities.
I am an spouse of a transman, and I have worked and communicated with hundreds of SOs, and I, too, wish more would come here to Susan's because it is a safe place, and a clearinghouse of great information. SPouses/partners could learn a lot reading the forums, and I think trans folks would learn quite a bit from the SOs.
We need much more dialogue between trans people and their non-trans partners-not only at home, but out here in the virtual marketplace of ideas.
I'm staff on Susan's chat, and I can be found in the #Chat lounge almost every evening sometime between 8 and 11 Eastern time. Do stop by and visit if you're an SO seeking info, support, or just affirmation that you are not alone. My forum name here is ftmshubbie, but on the chats I go by "dan." Hope to see more folks here and there.
D