The problem is that most people forget is that Radiant Servant is incomplete... while other classes get 2-3 complete(or nearly complete) prestige classes clerics only ever got 2/3rds of one now it seems the devs have spread the incomplete prestige out instead giving us the 3rd tier worth of new "useful" abilities... making Positive energy aura 5th tier is just lazy and unimaginative...
I used to imagine what "Cleric Radiant Servant III" would be like if the devs ever got around to adding it... like a light damage based energy burst or a Guard Effect that would triggers free Positive Energy Bursts... I honestly didn't expect them to just spread out 12 levels of prestige to 20 levels....
It's still early I hope things change for the better...