Wikileaks - iOS Exploits

I found an interesting page while going through the new Wikileaks dump.

https://wikileaks.org/ciav7p1/cms/page_13205587.html

When you go to this link you will see a list of iOS exploits, how it is done, when it was found, what version of iOS, who found it, who has access to it (CIA, NSA, or FBI) and more. The second list shows when new exploits were found with iOS updates. I began to wonder what iOS the San Bernardino shooter had on his phone when the FBI was trying to hack it, which was an iOS 7.
(https://en.wikipedia.org/wiki/FBI%E2%80%93Apple_encryption_dispute)

But you can clearly see from the leaks that FBI had access to iOS 7 exploits in 2013, so why, in 2016, was the FBI demanding apple to crack the phone if they already had the ability to gain access?

I am not an expert on this stuff so I could be wrong about what I am reading but I wanted to bring this up and point this out. If you have anything more to add please do so in comments below.

Edit to add link to iOS directory
https://wikileaks.org/ciav7p1/cms/space_2359301.html