imho, the problem areas with older characters are:

• thicker skin.  as people get older, their skin thickens.  this means noticeable translucent edges to skin and increased dermal (not subdermal) scattering. the lack of translucency is what makes the really old textures look odd, even if they have displacement.  i'm  not sure what to do about this.
• thicker eyelids.  V4's eyes often look swollen to me because the edges of her eyelids are so thin.  imho, this means for realistic characters over the age of 10 or maybe even 5, you have to obscure the edge with makeup (ex: Maelwenn's and Rebelmommy's textures), buy textures that have burned in shadow and specular that create the impression of a nicely plumped eyelid (ex: Shahara's textures), or manage to edit her eyelid.  M4's eyelids just seem plain strange.  the Unimesh line is good for up to about 40 or maybe 50, but after that, i think they should be a little thicker. 
• all over wrinkles.  most older figures have wrinkles on their face and a droopy build, but no large scale wrinkles anywhere else.  the neck and hands especially show aging.  most older characters are notablefor their young necks, shoulders and hands.
• drooping in more than the breasts.  triceps, flesh on the back and belly, and other places need drooping, too.  though, since this is a gravitational effect, i'm not entirely sure a single morph would do.
• knobby joints. elbows, hands, knees, wrists, ankles, feet and toes should all get morphed, and few people bother.  especially with the hands.  even stars ages often show in their hands.

all of those are hard to deal with.  the first may be impossible to address in Poser or D|S.   and since older characters don't seem to sell well, i'm sure the work seems less rewarding.