As Riot responses aren't that common, I'll give the relevant answers to your questions:
"she's extremely fun to play as a tank to boot!"
Good! Glad you enjoy playing it. Trying new things, experimenting with items, and having fun with off-builds are great ways to keep the game fresh and to have fun with League of Legends.
"Her win rate actually seems to be pretty decent,"
It's unfortunate, but it actually isn't. Akali is a champion who has been in a rough spot for a long time and needs some dedicated help. As for her winrate, if you look at high elo games, her win-rate is sub 50% more days than it's not and has dips significantly below that point and in Korea she is in the top 50 low win-ratio champions.
I completely get why it is a thing, as in what the goal was with the build: that Akali is an assassin but is in a bad spot and her low survivability is is made worse because of that, and since she has less burst and escape than other assassins, she just gets blown before she can do anything. So you get tank items to help her survive and do damage.
But it's a real bad sign when a damage-dealing champion has to build tank in order to then try to deal damage, damage said champion has not even bought.
"What are your thoughts on Akali building this way?"
Riot: "'It's a build that focuses on unintended strengths for Akali and using her in avenues she was not designed for.'
...Or to put it more plainly, regardless of the reason, it's bad because it's not our idea. Expect to see upcoming nerfs to Sunfire Cape and Titanic Hydra."