For instance, flash of light heals for what? 15k? A buffed tank will have nearly 150k health. That's 10% health healed for a spell that costs nearly 10% of total mana. That means I'll be OOM after I top the tank off from zero. Now, I'm not speaking strictly for Paladins because I know other healers have the same issues with their "expensive, emergency" healers having tiny throughput.
If you take time to remember what healing was like in Vanilla, it wasn't nearly as bad as it is now. My memory is quite vague, but I'm sure the "expensive" heals didn't heal for measly 10% of total health.
Also, if you look at it from the PVP perspective, this new change totally kills healers. It's either you OOM after 15 seconds, or you sit there casting 3 second heals, virtually asking for interrupts. For both PvP and PvE's sake, the healing throughput, at least for the "emergency" heals, need to be buffed a little; it's pretty ridiculous as is.