What in particular is bad about HTTP/2? Complexity can arise in protocols for multiple reasons. In this case, security and correctness are more culpable than anything else. That is, if you want to design something similarly performant, you are going to run into a lot of the same issues (flow control and priorities for fairness, issues with gzip compression, and so on).
At the risk of sounding too blunt: Everything? All of it? Its mere existence?
It fucks up responsibilities by addresses network-layering issues at the application layer. It takes a simple & stateless text-mode protocol and converts it into a binary & state-full mess.
It has weird micro-optimizations decided to ensure that Google's front-page and any Google-request with its army of 20000 privacy-invading tracking cookies should fit within one TCP-packet using American ISPs MTU packet-size, to ensure people are not inconvenienced when their privacy is being eaten away at. Which I'm sure is useful to Google, but pretty much nobody else.
The list goes on.
It does a lot of things which is not needed nor asked for by the majority of the internet, and yet the rest of the internet is asked to pay the cost of it through a mindboggling increase in complexity, and I'm sure a source of a million future vulnerabilities.
I'm not aware of a single thing in there which I want, and if I'm wrong and find one, I'm unwilling to accept that this is the cost I have to pay for that feature.
Any web-browser I will use in the future will be one where HTTP/2 can be disabled.
> It has weird micro-optimizations decided to ensure that Google's front-page and any Google-request with its army of 20000 privacy-invading tracking cookies should fit within one TCP-packet using American ISPs MTU packet-size, to ensure people are not inconvenienced when their privacy is being eaten away at. Which I'm sure is useful to Google, but pretty much nobody else.
However there were may other bad protocols that died through lack of use. You can still vote with your feet. A vendor will not maintain a protocol stack if people don't use it.
Hey, don't look so down... Poettering might be shipping an HTTP/2.0 library soon!
And yeah, I'm with you--I think that a lot of this tail-wags-dog stuff is going to come back and haunt us, but we as an industry fucking suck at being conservative when it makes sense.