I think it's fairly obvious that sony's intention here was not to challenge the one s at all, or market the pro as much of a 4k video player. This is a new 4k/hdr games console, well as close as you're going to get at the moment, that will massively help their VR along on it's way. That's all. The one s simply offers the same xbox one, in a smaller case, with a uhd disc drive. One that still cannot bitstream, making it completely worthless as disc player imo.
All new (and a fair selection of old) PS4 titles are going to be equipped specifically with the option to play on the pro. Specifically optimised for 4K and HDR output. They could, and probably should have, added in a UHD drive yeah. But as this is supposed to be a 4K console 1st, and anything else 2nd, this still beats any other console hands down for it's primary purpose.
Personally I couldn't care it doesn't have a UHD drive really. Yeah it'd be nice to have a spare, but id've never used it for that purpose owning a UB900 and my other 4K TV isn't HDR. Itd've made it at least another £50 more expensive as well. So for me, that's money saved. I do understand peoples disappointment, but to anyone in doubt about it's 4K HDR gaming capabilities, go check out the gameplay videos from last night. Specifically the one for Horizon. Phenomenal. It won't hit the native 4K gaming a $$$$ gaming pc will obviously, but come on its only £350 so it's all that can be expected. I imagine the PS5 will achieve that milestone in a few years time.
This however has gone wildly off UHD disc topic now though.