what would you want specifically ?

(Those are all just examples)
to get all typefind functions:
gst-inspect --plugins | grep "typefindfunction"
to get all GPL plugins:
gst-inspect --plugins --license | grep "[^L]GPL"
to get number of elements I wrote:
gst-inspect --author | grep "Benjamin Otte" | wc -l
to get all elements that work with float audio:
gst-inspect --padtemplate-caps | grep "audio-x-raw-float"

Is anyone going to work on this?

I doubt anybody wants to waste time implementing this.  For usage in scripts we have nice bindings to multiple scripting languages.  For people to quickly get to filtered information like this, I'm developing gst-inspector (which is faster and easier than using any command-line interface anyways).

It seems there's not a lot of need for functionality like this, but I'm not sure if this comes from there really being no need or people not realizing the potential.
That said, it doesn't look like anybody will be working on this, so if you wanna close it as WONTFIX go ahead. I still think it's a valid bug to keep open though.

Don't see much point in keeping this open. A more scriptable gst-inspect-query kind of thing would best be done as a new separate tool anyway IMHO, and I also agree with Rene's sentiment that scripting languages like python are much better suited for this kind of thing. Also don't *really* see the use-case for any of this.