I'm sure the "crappy" Blu-ray doesn't look all that bad on a 4K set.. lol.
My only complaint about moving to 4K is that they've effectively ditched 3D. So for new films, I can buy 3D Blu-rays, or 2D UHD, but never in the same box. And I have to hurry to buy a new TV soon, or I simply won't be able to get one with 3D, and I'm not quite ready to just give up on that. If you've seen Doctor Strange in 3D, you'll know what I'm talking about.