Why did Zarigan's Arcane Enlightment filigree set bonus change?

[KrazyKaster]

For those unaware...

OLD:

• 2 Pieces: -10% Arcane Spell Failure
  3 Pieces: +1 to your Transmutation and Conjuration DCs
  4 Pieces: +1 to your Enchantment and Necromancy DCs

NEW:

• 2 Pieces: -10% Arcane Spell Failure
  3 Pieces: +20 Force Spellpower
  4 Pieces: +1 All Spell DCs