Yeah, it'd be nice if Google search pages came with a handy "Link to this" button as Google Maps and Google Books do...but in reality, that would raise even more issues. If I understand Google's search mechanism...the results are tailored to each user...my search for "burger place" is going to be much different than someone doing it in New York. Yet if I see a "Link to this" button -- especially if it's a link shortener -- then I would expect it to direct all users to results that I've seen. OK, I don't expect that...but I bet 99% of other users do.
So it's not a clearcut decision about whether such a feature should exist, given the ephemeralness and personalization of SERP. So given that it's not an intended common use case to pass around URLs to results...what is it that Google should do to fix this? Re-engineer their system so that every URL is a non-human-readable URL that obfuscates all possible metadata? Remove the ability to tailor search results based on past results of that same session? I can see why they might choose: "If a user wants to send around a URL by manually copying and pasting it, we should trust them to read it before they send it out as the relevant parameters are human readable"