IPCOMP support in HIP

Why did we not create a parameter to negotiate IPCOMP (currently RFC 3173)?

In IKEv2 it is negotiated in NOTIFY messages, not the basic exchange and 
becomes part of the daughter SA(s).

On contrained networks, IPCOMP could well be of value.  Also if HIP is 
used to establish the SAs for SSE (draft-moskowitz-sse-02.txt) and the 
SSE payload is XML, then IPCOMP (or some variant tbd) may be a good thing.

So....

Again, why no IPCOMP parameter?

IPCOMP parameter handled like ESP parameter or like in IKEv2?

How to add an IPCOMP parameter?  If I write a draft for a Generic 
Protocol Compression, I can include a section that defines an 
IPCOMP/GPCOMP parameter.  Or I can add it to DEX (don' want to add that 
at this point, EC25519 fits, IPCOMP is expanding the protocol).

Comments?