excels so much at ganking early game after she gets 
and 
. When ganking the mid and bot lane (especially bot lane) the squishies like the adc or mid are just so easy to kill sometimes, after that she basically snowballs and carries. Why don't very many people play her in the jg? :/
She can't clear very well and she is horrible at ganking until she reaches level 6. Those are two problems that just compound each other. Not to mention that she doesn't hold up well against opposing jungler pressure early in games.
Sure she can snowball if she gets going after level 6 but there are a lot of champs that can do that and be more of a factor before getting to level 6.
Because it is rather bad..
A jungler isn't all about ganks. There are less gold in the jungle than there are in lanes; for a champion to be good in the jungle, he or she needs to be not (extremely) reliant on items, and have good sustain or AOE in order to maximize income.
Akali won't survive in the jungle, she cannot put out damage over a prolonged period, not does she have godly sustain. Her only perk would be her ganks, which would be lackluster because of how item dependent she is.
Because CC junglers is the meta, which leaves space to an assassin to go mid, things can get quite nasty when your team is all based in squishy assassins.
I've used Akali jungle before, it's quite fun, but not sure if I'd have the balls to bring her to ranked.
horrible clear easy to counter jungle horrible pre-6 horrible ganks horrible jungler
She doesn't put any pressure on the map for the first ten minutes or so.
She doesn't have great farming potential and is easy to shut down pre-level11. She also lacks CC in any form. It's like jungle Ryze.
She can't gank pre-6 and her clear is a bit below average so she takes awhile to get there.
