The technical details are all right (or seem right to me, anyway), but this is too opinionated for my liking. No, you do not need a 4K monitor for software development. Some people might like them, some won't. [edit/clarification: someone rightfully pointed out that nobody will actively dislike a 4K monitor. I was unclear here: I meant "some people won't need them" more than "dislike them"] This sounds like when Jeff…
(My first laptop was a second-hand HP 6710b at 1680×1050 for 15″, and that set me to never accepting 1366×768. So my next laptop was 15″ 1920×1080, and now I use a 13″ (though I’d rather have had 15″) 3000×2000 Surface Book, and it’s great. Not everyone will be able to justify the expense of 4K or similar (though I do think that anyone that’s getting their living by it should very strongly consider it worthwhile), but I honestly believe that it would be better if laptop makers all agreed to manufacture no more 15″ laptops with 1366×768 displays, and take 1920×1080 as a minimum acceptable quality. As it is, some people understandably want a cheap laptop and although the 1920×1080 panel is not much dearer than the 1366×768 panel, you commonly just can’t buy properly cheap laptops with 1920×1080 panels.)