Such a system would have to make a perfect assessment for one and it would have to be additive and not punitive. It also should not be a comparison among players participating but rather against the entire player base. Everyone gets the usual stuff, the good players gets a little something extra.

The assessment in itself would require SE taking a stance on what is deemed "optimized" play. God knows that's a can of worms in and of itself (anyone ready for a healer DPS debate? ).

But lets say they came to a conclusion and just handcrafted/tested some decent numbers to match in terms of healing/dps/mitigation for "above average play". Everyone above that could get bonus tokens to purchase dungeons gear or whatever.

That's the only way I could see this not being detrimental to players. SE has however taken stance against any form of player segregation in the past (aka no calling people out for not performing). It would be weird for them to implement anything of the sort. Fun exercise nonetheless.