In Nier, NIER was a person. That person AFAIK is not in Nier:A, so why is it called "Nier":Automata? There seems nothing in common other than the game creator and game structure (including the 'all my data is visually erased' gimmick). But "Drakengard" also had those in common.

NieR is a spin off series, not just the main character of the western release of the game which was NieR Replicant, NieR Gestalt in Japan.

You don't just throw away branding on your sequels.

@memu: there are subtle call backs to Nier in Automata but also I think it’s just because it’s in the same universe with similar gameplay.

It got Nier the top spot of this years GOTY, but not quite.

It's a direct sequel to the original Nier in the same world. There's a lot more in common than Drakengard.

As for why it's called Nier when "Nier" is not in it, branding, as someone else said. It's the same reason it's always called "The Legend of Zelda" even when Zelda has little to nothing to do with a particular game.

because it's nierly a good game

Because it is a sequel to Nier. Even though set ~10000 years in the future it is still taking place in the same world - with Nier's story being the foundation of its present state. Plus: lots of (mostly subtle) call-backs to the first game. 3 very familiar faces even show up.

Same reason why Yakuza is still called Yakuza in the West despite being a really misleading title. Brand recognition.

It doesn't feel like the same world to me. The world of Nier is magical and the world of Nier:A is technological. Plus there would be no surprise that all the humans are dead. But where did all the Shades go? Where are the "shells"? I did spot Emil's (magical) head, I think, at one point in Nier:A. Branding? ok.

brand recognition.

Neither batman nor superman are in Batman V Superman but that didn't stop them from calling it that

You should know where the Replicants and Gestalts went if you finished the original Nier. Hint: They're all dead thanks to Nier.

It sounds like you haven't gotten very far in Automata yet, so I'm not sure why you're questioning it so hard, but there are several very direct references to the original game that undeniably sets them in the same world. Also don't forget that the world of Nier was originally also just Earth several hundred years into the future. If the world can go from modern day Earth to Nier-land in a few centuries then the jump from that to Automata over thousands of years is not much of a leap.

The Twin Brothers are using magic, admmitedly without a book like Weiss and that is another mystery this game leaves up in the air. The world of Automata still has the same odd science-magic about it.

You might as well ask what the deal is with the Zelda games or Final Fantasy series.

The difference with Nier is it still takes place in the same universe, just so far in the future that it only marginally matters. It's a separate story with a shared backdrop, which is why it's called Nier Automata and not Nier 2. Even Popola and Devola make an appearance.

You could argue that the series diverges in such a way that it deserves its own title, a reason why the first Nier isn't just called Drakenguard: Nier, but the game still hits a lot of the nails we identified with the Nier experience. Endings behind endings, fishing for no reason, sudden shifts in camera angles, the powers you get are almost exact copies of Nier's abilities, etc.

@memu: It takes place in the same world as Nier and those things are not present exactly because of what you did in the course of playing the original Nier.