Might just be a not so good rub recipe. Diff'rent strokes for diff'rent folks and what not. And, I thought "real" texas brisket used coriander, but I might be wrong.
Another thing to take into consideration is how dilute the pepper was. For example a half cup of pepper alone is obviously overpowering if it's all your using, eventhough it doesn't seem like that much. It makes up 100% of the flavor profile. Take the same half cup of pepper and add it to another 2 cups of other spices and, obviously, the strength of the pepper-ness fades quite a bit because it's now only 20% of the flavor profile. Basically, the flavor/strength of any spice is directly related to the percentage of the rub that it makes up.
"Eating 'Que isn't making me fat- it's the beer I drink while lounging by the pit."