The exclusion of UHD Blu-ray support in the PS4 Pro is truly baffling; if Sony knew what was good for them (and listened to their consumers) they would do whatever it took to include it before the PS4 Pro launches. Un-freakin'-believable.
That said, I do not have a 4k television and have a PS4 Pro on order. My launch day PS4 often sounds like a jet engine, I'm constantly up against the 500GB storage capacity, and I can sell it to recoup some of the cost of the Pro. The graphical boosts are just icing on the cake.
The biggest thing I'll be missing out on is HDR, which is a shame. But any graphical fidelity/frame rate enhancements that can be achieved while rendering at 4k will carry over to the 1080p version of games as well. The only games which won't benefit on 1080p televisions are those like the Elder Scrolls, where it's the exact same picture/graphics but displayed at 3840x2160. I suspect those will be the exception however, and that most will go the route of Rise of the Tomb Raider, where the 1080p experience is akin to bumping a PC from "high" graphic settings to "ultimate".
A few things people (and developers) need to keep in mind: for one, this system isn't powerful enough to take a game like Uncharted 4 and render the exact same graphic fidelity at 4k while maintaining the same 30fps; you'd see that frame rate drop to something like 15fps if they tried. So most games will likely actually render at something like 1440p, and then either upscale that picture to 4k or downscale to 1080p depending on the connected display; either way will result in smoother edges.
Secondly, people also need to understand that on a 50" screen from 6ft away, the human eye can't even see the additional 4x the pixels of a 4k display. In the example I mentioned above, side by side between a 1080p display and 4k display you would not be able to tell the difference. There's a reason all of those televisions at the Sony event were like 120" and 2ft away from the viewers...
I think most developers will quickly realize that and instead of wasting all of that horsepower trying to actually render at a true 3840x2160, they'll spend it on enhanced visuals instead - which will benefit viewers on all televisions.
HDR of course is another story, an a true advantage for 4k television owners (no one makes a 1080p with HDR support). Unless you're rocking an 80" 4k television that you sit 8ft or less from, what you should really be excited about is HDR support because that's something you can actually see.
The list of games intending to take advantage of PS4 Pro grows every day and I hope to see that trend continue as we approach launch day (I'd love to see a patch for Doom, the first game I noticed to have some pretty low-resolution textures in areas); and I really hope the patches for Uncharted, The Last of Us & Infamous are more than just adding HDR support.
My only fear is that the absence of the most obvious feature - UHD Blu-ray - is going to hinder PS4 Pro sales so dramatically that there won't become a large enough user base for developers to bother with Pro enhancements this time next year. Then I'd really feel like a sucker for buying one.