She's not a bad support. She's a passive support in a meta that rewards aggressive play in the bot lane.
Having said that, it would be cool if Q's travel time was reduced for close range targets. It has a sort of delay that means firing it at your feet takes about as long as firing it at half max range >__>
Either adjust the travel time of Aqua Prison to target location or widen the range of the said spell. Or increase the number of targets allowed for Ebb and Flow. Or increase either the time limit, slow percentage, or total hits of Tidecaller's Blessing.
Her problem lies in her reliance to her ADC to initiate a skirmish, which is not good, especially in early levels. I think she was made with the devs in mind that she'll be good in team fights, which she is, but had the drawback of passivity during laning phase.
-Surging Tides lasts for longer -Aqua Prision stuns for longer or easier to land -Ebb and Flow mana cost doesn't match the healing -Ebb and Flow can bounce between Allies/Enemies, but prioritizes the current pathing -Ebb and Flow no longer has reduced damage/healing for each hit if it goes through "normal pathing" -Ebb and Flow loses 30% healing or 40% damage if it bounces from Ally to Ally or Enemy to Enemy. -Tidecaller's Blessing doesn't have an auto attack limit and lasts for ~1.5 seconds -Tidal Wave doesn't have the speed of a drunken passed out snail
Yeah best way to make Nami, Janna, and Soraka better supports is to somehow make everyone more passive in the bot lane laning phase. Maybe more gold for creep kills and less gold for champ kills.
To Janna's credit, she becomes a better support everytime a jungler that isn't Amumu gets nerfed. The jungle meta is moving towards a focus on guys with great teamfight initiation (Amumu, Chogath, Hecarim, even Sejuani is getting some love in the jungle), and Janna excels at countering that from a support position.
And I'm kind of okay with the idea that some supports are specialized picks. I think it makes the pick and ban stage more interesting. If one team wants to play a aoe stomp comp team with Amumu/Wukong/Kennen/Miss Fortune/Sona, and the other team figures it out and counters it with Janna, I think that's good. I'd love for League's picks/bans to be more competitive (Like Dota). It'd be more interesting than "Ban this guy because everyone knows he's overpowered and then ban these toher two guys because someone on the other team is amazing at them".