Have you improved since you first started playing?

[Teraluna]

To be honest, I have no idea. There's no way to get feedback in this game unless someone tells you you're doing it wrong but there's no guarantee that person knows what is correct either or just want to be confrontational. This is why meters are important but SE seem so afraid to put any into the game due to claims it will cause harassment. Funny enough the lack of meters is exactly what causes lots of harassment because of my previous point.

It's a two edged sword - introduce metering and the next thing you'll see is posted performances all over the place, public shaming the lower figures.

I think personal improvement can be judged without this. You know how much effort you've put into learning your class - rotations etc.
You know how much effort you've put into learning boss mechanics.

But it's not only this - what is improvement?

Are you going more out of your way to help people?
Are you more patient with others in the group who may be struggling a bit
Do you not rush off ahead when a new player is in your 8 man group and take time to give them tips during the run?

Improvement is a wide description, and rightly so.