Thank you!What a highly reasoned post!
I'd definitely use the device for environmental cleanup and pollution mitigation. And travel to beauty spots around the world.

A transporter would be really handy for that plastic island in the Pacific (to get rid of it), and to clean up oil spills, as long as it doesn't also scoop up anything it's not supposed to.
As someone pointed out, they were humpbacks.True, but transporter tech does also remove the issue of "can't afford to relocate to seek a new job".
Freight might still be needed - transporter tech in the Federation has payload limits (two blue whales and accompanying water seemed to be pushing it).
However, this was using a Klingon ship, and no matter how much Scotty must have tinkered with it during their stay on Vulcan, even he couldn't have brought it up to Federation standards.
It might have been easier on an actual Federation starship (but that's just my speculation).