My proposal to improve paladin AoE healing and mitigate some of the effect of Beacon of Light is to introduce a new Beacon spell.
Beacon of GloryThis allows a paladin to switch modes when Beacon of Light is not the best choice. It allows the paladin to AoE heal in high raid damage situations, while still allowing them to focus on a single tank. It matches the current style of paladin AoE healing in Holy Radiance, where the paladin is restricted to healing those around her.
Fills the Paladin with divine power for 5 min. Each heal you cast will also heal up to 5 raid or party members within 10 yards of the Paladin for 10% of amount healed. The Paladin can only have one Beacon active at a time.
You'd have to do something to Tower of Radiance. Maybe a simple "Extra healing done by Beacon of Glory is increased by 1/2/3%."