They were going to include a DPS meter for training dummies, if my memory doesn't fail me. That way, you can practice your rotation, share your data with your mates and improve if needed. I think they're still afraid of people harassing other in dungeons because of their performance. It's a valid concern as it actually happens (rarely, though) when you're paired up with players that use parsers. That's why they implement this in a controlled environment where you don't clash with other people's "opinion" about it.