It's part of the problem where they take a monster race of old and make them a friendly player species today. It requires rewriting the setting somewhat.
Settings either evolve with the player base or die from lack of use. Some evolve very slowly (but surely) due to a more niche audience, others swiftly due to a larger audience that shifts with the new blood coming into the fandom.
Forgotten Realms was pushed by TSR as their Mainline, Header "standard generic fantasy" setting in a sea of alternative niche setttings that benefit more from conservativistic (with a small c) holding onto their narrative ideals. When WotC decided to put the Realms front and foremost for D&D in 2014, they were making that same call that the 'Realms had to evolve to meet the Players where they are, rather than try to hold onto an idealized "golden age of D&D" setting that shouldn't ever be re-written.
2014 FR was also very big on resetting the Spellplague changes so that it looks like you remember from 2E & 3E, but keeping 4E's major timeline jump (something they also did between 1E -> 2E and 2E -> 3E) and just saying that we jumped just a little bit farther so that there was time for the Spellplague changes to undo themselves as Abeir moved back out of conjunction with Toril. So from a big wide angle lens, 2014 5E Forgotten Realms looks like it's very conservative (again small c, not talking politics here) in trying to be true to your grandpappy's 'Realms. But the D&D Next playtesters are not the only players playing 5E anymore. They contributed to its massive appeal, but gaming channels like CR playing the edition on YouTube and Twitch etc brought in a massive new influx of players with their own ideals about the game. The 5E player base has evolved over its 11-year run (and counting), much as 2E did in its 11-year run (with a mid-edition Revision in the Player's Option books, I might add).
The 2024 Player's Handbook was always going to be designed to meet the current D&D player base where they are (or where WotC thinks they are). That is not necessarily where you or I or most of EnWorld's posters are, but it might be. I grew up playing the OG WarCraft trilogy as a young person, and especially WarCraft III, where Orcs were given a much more nuanced approach compared to their "always chaotic evil" take in past games. Looking back, WarCraft III had a lot of what I'd now see as orientalist & and noble savage "cowboys and indians" sort of tropes in it, and Thrall, Son of Durotan is not free from those harmful stereotypes just by trying to lead his people to throw off the baggage of their chaotic evil kin (Yes, he's very much a Drizzt in Orc's Clothing).
In addition, that game starts us with Orcs in a very "Eurasian Steppe Shamanistic Horde" setting and moves them to a "Wild West Cowboys and Indians" desert setting; it's not very sneaky about it's two major influences in its tropes. But I far far far preferred the narrative of Orcs reaching for something primal and good and free in the wake of years of being the demonic horde bad guys, to them being the demonic horde bad guys faction (even if there were some goodies there trying to get rid of their addiction to blood magic). Oh yeah, addiction tropes was the third element of the Orcish problematic triad.
But, that era of fantasy storytelling regarding Orcs fundamentally changed how the fandom sees Orcs as a monster and as a species. We eventually got things like Legends & Lattes starring an female Orc barista just trying to live her normal cofeeshop life after settling down from her adventures. The popularity of that book series is just one more example of how the fandom has shifted -- and that fandom eventually comes around and reaches the D&D creators.
It helps that WotC already had a Half-Orc player species since 2000 in the core game, and it helps that they also wanted to get away from awkward questions about "half-breeds" in the Player's Handbook and leave that to individual players. The best way to do that was to do away with both Half-Elf and Half-Orc and just let such characters choose to either use the Human or Elf/Orc character stat blocks and describe themselves differently.
I'd note that Eberron specifically utilizes Half-Elves in such a way that the Khoravar species is almost necessary in next month's Forge of the Artificer book. Notably, thee Khoravar are not just 1st-generation Half-elves but also like the Tuathan of 4E's
Heroes of the Feywild and the Bretons of
The Elder Scrolls – a unique culture many generations old of immigrants and their descendants, and the Marks of Storm and Detection are unique to the Khoravar. Meanwhile, in previous Eberron lore, the Mark of Finding can generate on either Humans or Half-Orcs, so they can just go with saying that in House Tharaskh, there are Humans and Orcs and their intermingled kin (choose one or the other). The only thing this changes is that some Orcs without a Human parent now might have the Mark of Finding, but in -YOUR Eberron-*, you might say that those Orcs have a Human in their ancestry somewhere.
In any case, Forgotten Realms doesn't have the same sort of special cultural origin nation made up of "just Half-Elves" or "just Half-Orcs" so it doesn't have the reason to create its own non-Elf, non-Orc, non-Human but half-breed species (it does, however, do that for Tieflings because of how 4E lore shook out and their immense popularity but also now trying to bring back other types of Tieflings into the narrative). It DOES, however, have Orc cultures from past generations that could have changes with the passing of centuries. And it has the responsibility and the "Headliner Setting" to carry the default assumptions of D&D from the Player's Handbook (with the exception of its pantheon, since that is tied to Greyhawk and Planescape instead).
That means that since the new player base broadly likes the idea of Orcs as heroes (and prefers them to having a default assumption of Half-Orcs), Forgotten Realms needs a place for them. So it has to change to fit this assumption. Though again, this is all my assumption of what WotC believes that the Player Base currently likes because they have access to much more data than I do. I for one like this change for Orcs, but I also never much loved FR. Though these two new books along with some great 5E adventure modules set in the Realms over the last decade have given me a bit more interest in the setting.
*to borrow a Keith Baker-ism.
