The main reasons you don't see a lot of people using them at the moment are:
1.) The lack of readily available Masterworked ones. It is currently much easier to acquire one of the many, many +3 Awlpikes/Long Awlpikes already on the market than a +3 Ranseur.
2.) They are two-directional. Two-directional polearms were already less than popular as far as weapons go, and the turn speed change had a greater impact on them than weapons that actually have side swings.
Neither of these reasons has much to do with the weapons themselves, which are actually pretty decent as long as you're good with two-directional polearms. They don't need to have side swings or be able to be used with a shield, although there are some people think the Partisan should be reviewed a second time because they feel that the high damage cut thrust doesn't make up for the fact that cut is bad against high armor targets and that it can't rear horses.