Would you like an in-game parser?

[DeaconMoore]

In general people should figure out a decent rotation while leveling and practice on a dummy to learn it.

But in leveling is just a low gain out of a parser because of missing skills.
Also in casual content it really isn't needed. I'm running dungeons to get into the jobs flows in duties so i wouldn't want to be judged by my performance in a job i haven't mastered yet or i play to relax, that's what casual content is for.
In SSS and higher endgame content It is a complete other thing, cause it is a kind of competition.

And how do you know the rotation is good? How do you know what you melded is good? How will you find out if what you want to meld is better or not? A parser outside of endgame.

Yeah, it isn't needed in leveling content. Hell you can play just fine without one period. But being able to compare yourself and track improvements outside endgame helps you know what you are doing when you do hit end game.