I think we all think HPKP is an important security technology, but of course one that has to be used carefully because it can lock users out of a web site entirely for a period of time (for instance, if a server hard drive fails with no backup). We would like to give people tools to make HPKP setup convenient or automatic, but we’ll probably need some experience with how people are using it, what their backup strategies are, etc. The HPKP protocol requires servers to specify a backup key as a precaution, but it can’t enforce a system administrator’s actually making an offsite backup of that key.
If we have time, I expect that an HPKP option will be included in the client around launch, but won’t be active by default. (By contrast, we may give users a built-in option or recommendation to turn on HSTS, which is a bit less risky in terms of accidental self-denial-of-service. In the early versions of the client, activating HSTS is part of the “Secure Mode” option.) But again, we could benefit from more experience with how sysadmins use HPKP, how well they understand it, whether it commonly causes reliability problems or outages, and so on, before we come close to trying to automate it for the typical Let’s Encrypt user.