(I am moving this suggestion over from Jira! I'm aware that it was responded to, I just want to keep up with it.)
Second Life as it stands will only allow users to have 30 or so animations running at the same time. Any more than that and the user will begin to have issues with animations being dropped to start a new one.
I am proposing this idea because unfortunately, avatar posers on the Marketplace utilize set animations for users to pose themselves with. Attempting to use two different posers, one that poses the body and one that poses the face/fingers, will start to cause problems and make photo taking more and more hectic. There's also a lack of support for posing wings, tails, and ears (Sometimes the animations they come with don't cut it), so why not pose those yourself?
I feel that it would be beneficial for the viewer to support a built-in posing system to mitigate the amount of animations a user would need to use just for photo taking! An efficient feature that could possibly be used alongside animations, but would take top priority over any animation running on a specific bone.