As I've said in other threads, every class that has had stances in every game ever made had penalties for stance switching. It's meant to make you think of when to switch stances instead of doing it rotationally, or (as seen throughout HW) get an aggro lead and pretend you were a DPS.
Now, to show I'm not entirely heartless, I can suggest one way to get stance dancing back, but it would require removing every bonus from Deliverance and Defiance (no increase in max HP, no aggro bonuses, no crit bonuses), and instead have them alter the effects of individual skills (for example, Berserk behaving differently depending on which stance you use it in). You'd also need to do more combo juggling because your threat bonuses would come from a combo effect, which means that if you want to hold aggro you're going to keep that threat bonus active most if not all the time, combined with other passive mitigation effects from combos. And that would be on top of still managing the Inner Beast gauge for consumption on damage or mitigation skills.