Indeed. In my experience, looser requirements in this kind of thing just leads to tears on the part of client and server implementations. I'll happily reduce some of the MUSTs to SHOULDs or MAYs if it makes sense for the communication channel to consider them optional.
That's great to hear. One particular example which I found needlessly strict is this:
The request MUST contain a Content-Type header whose value is
application/json. It MUST also include application/json as the only or
highest quality factor.
It makes sense for fully compliant implementation to have those headers, but they way I understand MUST here is that a server would reject any request without them.
