Ditching the Sony A/V adapter is fine at this point, though I thank Sony for keeping it the same on the last three gens.
As for external hard drives, are they saying they're not supported at all, or you just can't use them to store gaming? If the latter, that's not big deal since we didn't have then before. If the former, that's a bummer since I know a lot of people who use external drives to store movies for playback.
4K display is no-brainer. All but the most powerful computers have trouble with 4K gaming today. I guess it would have been nice to have 4K playback support for movies, if not games. But not a huge loss.
Strange that DVD and Blu-ray isn't available in the shipping ROM. My best guess is they were still tweaking that part of the firmware by the time they had to start shipping these things around for launch.
Losing music and media streamer is really stupid, though. A PS3 made a great media server or streamer. MP3s meant some games had custom soundtracks capabilities ( I liked that in PAIN and Burnout Paradise. ) Don't understand why you're ditching it unless Sony is hoping to force people into their services. I'll hold out hope that like the DVD and Blu-ray support, this just wasn't done in time for shipping firmware and will be added later. Still, to not have it at launch is bad form, Sony.
Paid multiplayer, I'm not happy about, but I plan to keep my PS+ membership for the sales and discounts. It's still cheaper than XBL and at this point I think the two services are about equal, maybe PS+ is a little ahead thanks to its Instant Game Collection.