Let’s be perfectly clear here, this question is not meant to be theoretical but personal. Whether or not DPS numbers should be in World of Warcraft is a debate that has appreciable points on both sides and is also irrelevant, because the tools are already there and you can’t put that particular cat back in the bag. The question is whether seeing those actual numbers helps you improve or not when you play the game.
For some people, it definitely does. If you’re still learning your rotations and committing them to memory, it can be helpful to, say, see how much a different rotation helps you out on Death Knight. You can compare two pieces of equipment and see which one is actually producing better numbers even if one looks like it should be the clear winner. Maybe a lower-level necklace in Final Fantasy XIV is actually more useful because the higher one has Spell Speed and that doesn’t help you!
On the other hand, the number isn’t indicative of overall performance like following mechanics, and some people find that chasing the number only gives anxiety rather than goals to strive for. So what about you, dear readers? Do DPS meters help you personally improve your play in an MMO? Or are they at best neutral and at worst harmful? (Leaving aside the guy who wants to brag about his numbers. That guy’s just a jerk.)