Predictable
HTTP/2 is a highly complex protocol so it's very unlikely we'll see a fully correct implementation within the next few decades. On the other hand, laboratory tests only show about 30% performance improvement compared to unoptimized normal HTTP.
If I was a secret service I'd do my best to promote HTTP/2 as it'll mean lots of bugs and therefore many exploitable security issues. Any kind of complexity increase helps those who want to exploit it.
Biting the hand that feeds IT
