In my opinion an in-game parser is a very good idea (at least with the option to display your own dps, for research and self improvement purpose).
Last time in fc chat we were speaking about the use of a parser. We finally ended up with that analogy : when you are raiding, it's like you are driving a car. Now for example Faust in A1s could be a speed limitation telling you "if you don't drive at least at 110km/h then you can't enter this road". That's where parsers are useful, how can you know at what speed you are driving without something displays you the number?
Then okay some ppl will say "you'll know that your dps is good when you'll beat the fight". Ok, but sometimes that means waiting months to earn more gear, while the problem isn't the stats of your armor but your skill rotation. You can still try to blindly test different rotations, but how can you know if one was better ? Are you driving at 30km/h on a highway because you don't know if you are pushing enough on the pedal ? (if so, i'm glad to just meet you in a game and not in a real car)
I am pretty sure 99.9% of the persons raiding in that game are looking on google for guides about what is the Best in Slot gear for their job, what is the best between spell/skill speed and determination/crit etc... How do you think all that theory-crafting is made ? SE never released the algorithm used for the calculation of your damages depending on the det/crit/ss, so ppl had to try by themselves, using different gear, spending hours looking at the numbers of their parsers on different situations to end up sharing their ideas with other players about what they think is the best solution to improve your gear/rotation etc...
So, ok, some ppl are bullying players in dungeons trashtalking about dps numbers and things, but for the ppl who are trying to help the community, sharing their results about BiS and skill management (and i can tell you, it takes hours to see a difference between two rotations because you first have to master the new rotation at 100% to really see a benefit) we should all be happy if a legal way to mesure your dps was added in the game.