It would require 4 models for each pair of pants.
1 for upper left leg, 1 for upper right leg, 1 for lower left leg, 1 for lower right leg...
Might be too much of a hassle.
And besides, the villager model (or any other model) doesn't have attachment points for upper leg parts so the pants attachments wouldn't work (without creating new attachment points)...
So, it is possible to make pants but I don't think it's worth all the effort