That would be nice, but from a business perspective they made a better case for getting Neo. Besides if you can't afford a Neo, then you probably don't have a 4K HDR television that would benefit from UHD Blu-ray.
Of course they did, it's a well known strategy to make the cheaper product look worse and get people to buy the more expensive option. But from a consumer point of view it's never great to be "left behind".
And i don't get your second point. In fact i haver never understood that reasoning. It's not like buying a 4K TV means you have unlimited money to throw around. A lot of people have to prioritize what they buy. It's also about the future. I bought the PS3 back in the days even though i had like 2 blu ray movies. But i knew that i would get more in the future. It was pretty much the reason why i used it instead of my Xbox 360. I even ended up moving it to a summerhouse/vacation/holiday home(not sure what it's called in english).
It just smells a bit of Sony trying to get a few more bucks from the PS4 slim by not including a UHD player. But lets see how they price it.
To me it just reminds me of the Xbox 360 vs the PS3 and how i ended up liking the PS3 more as a media player because of the blu ray drive. The PS4 Slim is pretty much obsolete for people with a 4K tv as a multimedia player.