Specificity makes the damage formula more difficult, so the outcome is less obvious.
We need to test different things to see what leads to the highest dps.
If all specificity was removed and brought back to just one damage stat, we could simply read from the screen what gives the gives the highest dps (an accurate attack power reading instead of a rough estimate).
Then we would probably call the game shallow.
It also gives a choice you otherwise wouldn’t have: boosting all your damage with multiple different sources (low +damage%), or go all in on a specific skill and boost that (high specific +damage%).
I prefer to be kept in the dark a bit, so I don’t see it as much as a problem.
Using high percentages is a problem though, because damage goes rampant, with balance issues as a consequence.