i dont recall seeing sakura ever use genjutsu and this slug sage mode thing is questionable seeing as how i have never seen it.
but anyway i agree if she was properly written and developed she she would have being a really great ninja possible abilites list could include:
1. 100 healings
2. insane strength
3. genjutsu detection genius
4. have advance medical techs like kabuto
5. i am not sure what's up with the inner spirit thing but it defy ino's soul transfer
6. possible immune to poison not sure its questionable
7. lol slug sage mode...questionable
8. training with lee could improve physical feats
9. training with kakashi could improve strategic feats
10. what ever great chakra control gets you.
there could be more idk but kishi has his reasons as she would have being a great ninja.
Sakura already have these fears naturally
Kabuto is the inferior medical ninja , Sakura have far more feats tha kabuto she just doesn't use them for dark purposes
Her genjutsu detection is probably the stronger in the series bar sharringan users
Her inner Sprit is very much active, you know Sakura willpower is one of the stronger, able to fight despite being paralyzed by sasori poison
Again Sakura isn't a dark medic , I'd she wanted to she would give herself body modifications , but she has moral. Also Byakugou GG, and her fighting style revolves around not getting hit
Lee wouldn't teach her anything, Tsunade is superior , base Sakura did damage that the 7th hate couldn't
Sakura is overall smarter than kakashi, and even the better analyzer , as seen when she read Tobis jutsu
The thing with Sakura is that she is a product of the plot, she most have much more up her sleeve, but she doesn't need to use it , or Naruto will have a new rasengan to show off