If you've done nothing wrong ... you have everything to fear.
"it provided visibility of 96 cyber-attack campaigns"
Note: not stopped just provided visibility with no mention of before, during, or after.
“not in the slightest doubt that bulk interception, as it currently practiced, has a valuable role to play in protecting national security.”
Well, indeed, but so does rounding up all <insert current fear group> - it doesn't mean we need to, or should, do it.
"These include the detection and conviction of a UK-based airline worker who planned to use airport access to launch an al-Qaeda attack"
Who would have been uncovered by traditional means, no need to spy on 64,999,999 innocent people's communications.
"a group who travelled to Pakistan for terrorism training, who were arrested and given lengthy sentences under the Terrorism Act"
Who had done nothing wrong! Preventative justice. And surely you knew they'd travelled to Pakistan without spying on everyone else. And since you knew they'd gone to meet some bad people, you were already spying on the bad people so had absolutely no need to spy on the rest of us.
"the finding of two men overseas who had blackmailed children into exposing themselves online, who were subsequently arrested and jailed in their home country"
As nice as this anecdote is, it's not really in the remit of GCHQ, or a good reason to spy on the British people. And if these perps were British then you have said they wouldn't have been caught because that's internal communications. But, hey, why not throw "won't someone think of the children" into the mix?