I used and loved iPhoto and then I had a great (first impression) of Photos until I tried to do the thing you describe: DRAG AND DROP. Apple forums provided an answer (I would call it a work-around) with their usual condescending tone: hold Alt while dragging, and you can at least get a copy of the photo/video of interest into a folder in the Finder.
I just tried it in Photos 2.0 (macOS Sierra 10.12.3) and it works as expected - drag'n'drop from Photos to Finder copies files into selected Finder folder.