1) It might send a false message that Blizzard endorses meters as a performance evaluation tool, when fights are about more than meters (dps, threat, damage taken, healing done, overhealing, dispels, or otherwise)
2) It would encourage misuse of those meters
Frankly, both of those arguments fail, for four reasons. The first two are weak, but the third and fourth are pretty damning and conclusive:
1) Meters are being used well and misused already. You can't stick your head in the sand and pretend they don't exist or matter. The question is only whether the meters come from an unreliable 3rd party source or an in-game source.
2) While a single meter (dps only, or healing done only, etc.) is not an appropriate tool for evaluating performance, having multiple sources of information *is*, in fact, a useful tool for figuring out what's happening. If, as was the case in my old guild, we hit 6min on Garajal with only 2 healers and he's not yet dead, dps *is* in fact the problem, and wanting to know who needs to pick up their game is a valid concern. On the MV trash in LFR, I can pull up dispels, and if one healer just isn't dispeling at all, I can whisper them personally with a tactful request instead of idly ranting or embarrassing people in public. Those are two examples, but really there are countless others. Is raw dps valuable in and of itself? No, but no one's arguing for a raw dps count only; we're asking for data analysis tools (note: tools plural, not "tool"). These are tools we currently have to get from a third party, and whose considerable limitations we have to accept before trying to use them.The notion that meters do not describe performance or are not useful for raiders is wildly inaccurate and I'd even venture to say dishonest since Blizzard really does know better. Data collection is a good thing.
3) Blizzard ALREADY HAS (more accurately: *has had for many years*) an in-game meter in use. BGs and Arenas already measure damage done, healing done, HKs, deaths, and some other numbers, and post them for all to see. This "argument" that Blizzard doesn't endorse meter use is nonsense. They do, and have for a long time, just only in one part of the game, and paradoxically in the part of the game where total damage and healing numbers are even *less* meaningful because of the incomparably larger number of context-dependent factors involved in pvp. At least with raiding there is a boss, and people are in general doing comparable tasks. What difference is there between the meter already in place in the game for pvp and the ones people have been requesting for pve? The only major qualitative difference I can see is that people want more data--damage targets, spells used, damage taken with sources (i.e. how much people stood in fires), etc.--from pve meters. That goes back to point (1): raiders are not, in fact, so single-minded as to care about total damage alone and misuse those data while ignoring the rest.
4) Ghostcrawler and the other developers also EXPLICITLY ASKED for parses from players that *required* the use of addons when providing theorycrafting feedback in their beta thread. The developers themselves called for people to report the results from meters, indicating the value they place on them.
- This is a quality of life improvement. I want to know how I and other healers are doing, how the raid as a whole is doing, and what we could do better when the boss hasn't died yet. These tools help figure that out, and they would be made more reliable through an in-game tool.
- You already have a tool you endorse, and use it in one of the least appropriate settings possible. It's not a matter of official endorsement, misuse, or what have you. It's a matter of using data from the whole instance or from a single player's computer.
- It would affect a large number of people, it has been requested innumerable times, and it would require very little new programming. According to Ghostcrawler's own rubric, that's exactly the type of addition you should *have made* many years ago.