I don't think Lulu's passive scales with her target. Help Pix scales on Lulu's level and a % of her AP, and Lulu support often has little AP and is usually the lowest level on the team. Only useful on Auto Attackers and best on those with a ton of AS, since the scaling of it has nothing to do with the target.
Janna does have more of what I'm thinking about, but that's only for AD. Sure, she can support a mage and maybe if the AA a lot, they'll actually get some use of that. But the last time people thought... "Man, Janna's shield gives her partner so much free damage" it got nerfed. [V6.6] I guess we can't have offensive shields that mitigate too much damage. Oh... wait... that sounds like Shield Bomb. Don't know why anybody wonders why this isn't being brought back.
I'm not saying the AD/AP buff is the best thing since swiss cheese. There are plenty of runes that stack adaptive damage in the game (albeit in small quantities). But if we want originality, Karma needs to get out of the Shield business.