Honestly I thought you gave a pretty well reasoned remark and list of reasons why she's not really a tank is excellent. Couldn't have said it better myself, especially since all things considered I am kind of a newbie towards this game and don't know every single heroes mechanics and abilities.
I mean again, she does look fun to play (even though I certainly won't, I hate melee heroes, hahah), but tank she is not I'd say.
I've been on board with League of Legends for just short of a year now. This game is great in that there is so much to learn. The only downside is that there is nobody to teach you xD. The tutorial explains so little about the game, they need to release a more advanced tutorial.
It's the little bits of information that aren't in plain daylight that give you a competitive edge. For example, knowing the timers on all of the major buff monsters. (Red respawns every 4:00, Blue every 5:00, Dragon every 6:00, Nashor every 7:00) Being able to predict intercept paths of enemy team-mates before team-fights. (Essentially catching 1 guy alone before you give the enemies a chance to group all 5, 'causing your next fight to be a 5v4 in your advantage). Things that just take a lot of gameplay experience to learn xD. Hope tips like that help you =p.