True but when you choose The Light Within for the bonus you are Gaining +10% Attack Speed(not haste so only really effects white swings) and +10% AP, but you are losing (potentially since it hasn't been confirmed) 2 GCDs every 20 seconds to maintain the two buffs. With zero haste that's 13 action events, with 7 HoPo generators and 6 fillers. THW forces you to dump 2 fillers for seal switching.
I state it at zero haste because even if you have 50% haste, rather than zero, you still lose out those 2 fillers regardless, you just compress the rotation a bit to open up room for additional HoPo generation.