Janna sucks so much, when I play her it's like I'm AFK

Janna doesn't suck. She blows.

Janna's great when played competently. She's excellent at zoning off enemy harrassers and great for disengaging. If you feel like you are AFK when playing her, they you are probably playing tourist, just sitting behind the adc, making him 1v2 and struggle to get onto his cs. Not cool bro.

Good.

It is actually possible to play a harassing annoying Janna in lane and fall back to defense / disengage later.