I don't really see the trend you're speaking of, but that might just be me. I don't hunt the solo threads. I generally post my idea and let people come to me. Yes, most of my roles are M/M, but I do a lot of M/F. I generally take on the male role because I've been playing the male character in roleplays (adult and non-adult) for over ten years. When I first started roleplaying, most of the partners I found were other females and not interested in playing the male role. So I took it on. It was a challenge for me.
For me, I do play a lot of strong, male roles. Not just physically strong men, but mentally strong ones. That is how I prefer it. I do not want a sparkling vampire (or a vampire of any sort), nor have I noticed a surplus of Naruto type games. Then again, I have a strong inner circle of writing partners, so perhaps they have spoiled me.