True, the ps3 quickly turned the blu-ray  hd-dvd format war around. People did get curious about blu-ray after getting a blu-ray player with the ps3.

https://www.engadget.com/2008/02/20/two-years-of-battle-between-hd-dvd-and-blu-ray-a-retrospective/
In retrospect, it was the PS3 and its owners who won the war for Blu-ray. Despite what many believed, PS3 owners were buying Blu-ray movies and although it was a small fraction, it was enough to convince the studios Blu-ray had the most potential to be the next physical format

However it was a game changer for the movie market, not for game consoles. The ps3 outsold the 360 hd-dvd add-on 5 to 1 from the start, enough of a difference to give blu-ray the edge. 360 was outselling the ps3 despite all expectations.

This time Sony has no format war to win, the fraction that will be tempted to buy 4K UHD discs because the drive is included will be a whole lot smaller, plus it doesn't make Sony any extra money to stimulate disc sales.

On the other side you have a small faction that wants an UHD player for their new 4K tv. But Sony as a business wants you to get ps+ and stream content, that's where the money is. A console used as a physical movie player is a dud business wise. They know ps4p is the only console offering (half) 4K visuals for at least a year. I guess they rather have as much of the 99% that wants to play games in better resolution than lure in that tiny slice of 4K blu-ray buyers that plays the odd game as well.

It sucks Sony is making all the right moves as a business now. I liked them a lot better while susidizing me a shiny blu-ray player back in 2006. Ofcourse the early standalone players sucked (even became obsolete pretty fast) and were $1000+. A standalone 4k UHD player can already be had for under $400. It won't be long until the XBox One S loses its price advantage to a dedicated player with more features for movies and sound.

My bottleneck to the 4k jump is outrageous prices for 4K projectors. I bought a 1080p projector in 2007, still use it daily, still great. If 4K projectors get under $4k next year I'll be temped. Then I get to decide whether to get a standalone player with dual hdmi out (for sound), or get a Scorpio and a new hdmi 2.0 compatible amp. (Only way if it doesn't have dual hdmi out) A standalone player is suddenly a lot cheaper.

I'll reevaluate in a year whether 4K UHD discs become a thing made from actual 4k masters with most new movies coming to 4K discs. I still have plenty blu-rays to watch.

Maybe they'll release a Ps4pro slim or Ps4proelite LOL.

There is no need for them to subsidize the hardware in order to include UHD BR support, do you think MS is subsidizing XBone S?
Kerotan introduced the claim that UHD BR would be expensive requiring either subsidies or significantly raising the price,
but whenever asked for specifics on part prices to back that up, simply never responds to the issue.  Sure sign of confidence there.

As other posters have already referenced, simply looking at part prices for PC BR drives shows the price difference to be negligible (~$10 single unit).
(and Sony would not only have large volume, at-production-cost pricing, being a producer, but doesn't need to pay licence fees either)
So without needing to subsidize it at all, we are at most talking about a $5 price increase, which would not affect sales #s.

There is demand for UHD blu ray from videophiles, but they would buy a proper dedicated player to begin with.

I think its wise because theres alot of physical media buyers plus it benefits none gamers aswell.

I hear ya, defending and trashing 4K at same time seems exhausting.

I dunno, it just seems really odd a device leaning so hard into 4K wont support UHD discs. Frankly, who predicted PS4 Neo wasnt going to offer UHD support? It seemed like common sense.

Maybe they make a PS4 Pro Slim in 2019, a year or so before the Playstation 5 launches.

This depends on what proccessing node they currently made the PS4 Pro on, and if theres a new node for manufacturing avaliable by then. By 2019 maybe 4k TVs are much more common, and demand for 4k Blu-ray has gone up? if so I could see a revised version of the PS4 Pro, that has a UHD drive.

Everyone is mad because Sony didn't add it but no one stops to wonder why?  

My guess is Sony (the company I've seen stated of all companies that should have it because they're invested in it through entertainment and tech) has some data that suggest it's not as big of a deal as being made.  It's the most logical conclusion.

i thought it was odd to not have until I actually stopped reading internet rants and realized I was someone who went from around 500 dvd collection to 5 blu rays and when I buy 4k will likely not buy a single one.  Why?  Because streaming is much more convenient.  I don't want to have another expensive collection that's obsolete in a few year when the next big thing comes around.  That's the lesson I learned when I sold off my dvd collection for peanuts.

I imagine I'm not alone in that thinking and I further imagine Sony has data that backs it up.

It does seem odd unless they have data that suggests it's not as important as it's being portrayed.  

You're leaving out one key detail.  My logic is it costs more to do it now,  but it it's much cheaper in a year then why not.  It's not going to cost much.  They've nothing to lose by throwing it in. 

Sony focused on the games firstly and then on the media secondly.  It's funny how Microsoft don't have anything nearly as popular or as good as ps VUE and they were the ones focusing so much on the TV aspect of things.