Special:RunQuery forms are unique in that they can be easily embedded. It would be very helpful if these embedded forms can be dynamically preloaded with data from the page they're on. This can already be done with links to forms, which is how normal non-embedded forms are used.
Although it would be handy for all embedded (or transcluded) forms to be able to be preloaded, I think the Special:RunQuery embedded forms are a special case where it would be most natural. Instead, it appears the only option is to use a manually constructed link to the non-embedded form, as described here:
Which, of course, means the embedded feature of Special:RunQuery forms cannot be used if data needs to be preloaded.