Let us (boys and girls) assume that we will not get llGetLinkPrimitiveParams anytime soon if ever.
So how about we suggest methods like this to open up the possibilities of the other functions so that we can do more without the need for llGetLinkPrimitiveParams.
For example - To use llSetLinkPrimitiveParams to change the color and texture of a face we must establish all the offsets and rotations etc. This info is only available to us by llGetPrimitiveParams sent from a script within the link. Yuk. So we resort to using llSetLinkTexture and llSetLinkColour because we just wanna change the color and texture not fiddle about with all the other bits. And since we dunno what they are without writing it all down or adding further scripts it's a good job too.
So in order to free up some extra use of llSetLinkPrimitiveParams I suggest the creation of a new Constant PARAM thingy like PRIM_TEXTURE but without all the params. Just key and face(s). This way we can use llSetLink_ more than perhaps we do and worry less about the gaping holes in the list of functions.