Also the cite I'm looking at says she has an almost 1% ban rate which is about the same as the rest of the support champions. No one wants to ban a support when they can ban mages or skirmishers. The only supports that have high ban rates are mostly mages that could also go mid and they might have been banned for that reason.
http://champion.gg/champion/Janna/Support
0.57% ban rate as of 7.2.
Zyra practically never goes mid (91.08% play rate as support), Malzahar now sees almost 3/4 of his play as support, Brand 2/3, Morgana 80%… These are champions that could go mid, but very rarely do, and they all have higher ban rates than her. Even Leona, the exact opposite of Janna in terms of supports (hard engage vs. hard disengage), has a higher ban rate than her.
Zyra, Malzahar, Morgana, etc. are not getting their bans that high because people are scared of them in mid.
What about her kit is actually avoidable?
Where did I say "avoid"? I said "predictable," "simple," "basic," but not "avoid." And again, because it is those things, it is incredibly easy to outplay. And if your best interpretation of "team coordination" is "kill them" then that kinda tells as to why you'd think Janna is OP in the first place.