Why they want to have the tallest figure is an unknown. There is the fact that real sized figures in Poser are not popular. You have Miki and Roxie neither of which was popular, however you have Vicky and La Femme etc. which are very tall at least that what Poser says. It might have to do with the fact that Runway model females are the thing that all users want to be or to be with, since Poser is a fantasy world why be stuck with the boring real world? Maybe it is harder to make short figures taller instead making a tall figure shorter?

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13