Always mystified by this kind of comment. I countercharge all the time with halberds, straight into Mongol heavies and high royals, I just love it when cavalry charges my halberds. Makes my day.
There are lots of units that can charge into mongol heavies and cause damage but only a few have as poor a morale stat as halberdiers, billmen have decent morale and wont waver as easily if flanked there lack of armour is made up for by there speed and morale.

Besides i think halberdiers are better used on infantry its to dangerous sending them against cavalry alot of the time, id rather have them hacking into feudal men at arms and lower class troops than them doing the job of chivalric sergeants or feudal sergeants etc.