You can not judge joke fights as the basis for healing. When I "heal" a heroic I dps and I can keep people alive with sacred shield and instant flash of light from IoL. So obviously this means a good paladin only needs sacred shield and a chance at a flash every 6 seconds?
When I talk about how a paladin should be healing I am referring to how they should be healing in a fight that is actually straining the group. I happen to take this heal style and use it on all 25 man encounters because I see no reason to get complacent.
And no numbers have been posted to show that ret helps the raid more doing light. All you showed was that a ret doing JoL was stronger then a holy doing JoL which is true. No where did you show numbers comparing wisdom to light and you can't because you can't quantify the differences in what they do.
The real test is this...if you have 1 paladin in your raid what will people notice the least? I can tell you that is JoW is not up dps starts complaining in 5 seconds and there are people screaming on vent for it. If I was assigned JoL I could never use it and the only person that would notice is me because I would not have my haste buff. The healing is nice to have when you have 2 paladins but it really does not do that much. Pretty much the only fight where JoL is doing constant meaningful healing is saphiron.