No dev who has worked on Luminous engine has ever said that though, in fact I have quotes where XV devs have said the exact opposite. Anyone who's ever said Luminous was difficult to work with were gamers on various forums making assumptions and being armchair analysts while using KH3 switching over to UE4 as their proof, but let's break down the whole engine switch, and it's not because Luminous was difficult to use. It wasn't even the KH3 dev team or director's decision to switch.
KH3 switched to UE4 some time in late 2013-early 2014 because it was a company-wide decision from the higher ups at SE to start co-developing Luminous engine with only 1 game in order to avoid the same development issues Crystal Tool had, as recommended by Julien Merceron.
As a reminder, KH3 had an even longer dev time than FFXV even after it switched over to UE4. FFXV rebooted from scratch in 2012 while borrowing VersusXIII concepts and gameplay prototypes were made in the ps3 Ebony engine (parts can be seen in e3 2013 reveal trailer). XV development then fully migrated over to Luminous in late 2013 and released 3 years later in 2016; that's a really tight and short dev time given to a team making their first AAA open world title alongside developing a new engine. KH3 had 4 years of dev time on UE4, and this is after they had made prototypes in UE3 as well as Luminous. And despite KH3 having a longer dev time in UE4 it also wasn't as technically demanding as XV considering it had linear levels, no open world, no dynamic time of day or weather, baked lighting and shadows, but yet it still also had performance issues and horrible frame pacing problems.
So why does VII-R look better than KH3 (another UE4 game) and is more consistent looking than XV, and performance (at least for this very linear demo) is generally more polished and better than both XV and KH3? Huge factors is the longer dev time (VII-R production already started in 2014 on UE4, ~6 years of dev time on UE4 vs. XV's 3 years on Luminous), that's a big time difference for artists to refine their work and for programmers to optimize code. The VII-R team also only has one platform to focus and optimize for at the time of release, essentially giving them the same benefit first party exclusives have. They'll have an extra year to develop ports, whereas XV needed to be optimized for multiple platforms at launch on an already tight schedule. Technically XV is doing entirely different things whereas VII-R is more linear and uses renderfarms to create pre-baked lightmaps, which in this gen is always to going to be easier to have consistent quality compared a game with more dynamic worlds and lighting. XV is also about to reach 4 years old at this point...
and it's not like XV is a slouch in graphics compared to VII-R anyway.
https://u.cubeupload.com/chinhvu/619FINALFANTASYVIIREMAK.png
https://u.cubeupload.com/chinhvu/ffxvs201906062302566.png
So you can't really say this certain game is technically good or bad due to the engine before factoring in a bunch of other stuff. UE4 isn't some magic easy-to-optimize general creation tool either given the notable performance problems and lack of polish many other AAA games on it had (Days Gone, Star Wars, KH3). Development time plays a massive role in this.
And again the KH3's switch to UE4 wasn't even the director or dev team's decision. KH3 co-director talks about the switch to UE4 in a post-mortem about how difficult switching over to UE4 was for them since they had never used it before. They hit a lot of brick walls, and it's only thanks to Epic support this game was even made.
https://www.usgamer.net/amp/kingdom...e-spoilers-gdc-2019?__twitter_impression=true
"We were first trying to test the game on Unreal Engine 3," Kingdom Hearts 3 co-director Tai Yasue tells me during this year's Game Developers Conference. "Then we switched to Luminous. Then we shifted to Unreal Engine 4, and that was a corporate decision. So it wasn't really me deciding that I wanted to use Unreal because of this and that; it was a decision from the top."
"It was a tough switch, Yasue says, because the team working on Kingdom Hearts 3 wasn't used to the new engine and had to learn it from scratch—even the differences between Unreal Engine 3, where Kingdom Hearts 3 was once tested, and Unreal Engine 4 were astounding. Luckily, with Unreal Engine 4 creator Epic Games available for help along the way, the switch eventually worked out very well. "We hit a lot of brick walls, but someone was there to help us out," says Yasue. "So I think that's a major thing, connecting to people. It's not just the technology and the engine."
"We were first trying to test the game on Unreal Engine 3," Kingdom Hearts 3 co-director Tai Yasue tells me during this year's Game Developers Conference. "Then we switched to Luminous. Then we shifted to Unreal Engine 4, and that was a corporate decision. So it wasn't really me deciding that I wanted to use Unreal because of this and that; it was a decision from the top."
"It was a tough switch, Yasue says, because the team working on Kingdom Hearts 3 wasn't used to the new engine and had to learn it from scratch—even the differences between Unreal Engine 3, where Kingdom Hearts 3 was once tested, and Unreal Engine 4 were astounding. Luckily, with Unreal Engine 4 creator Epic Games available for help along the way, the switch eventually worked out very well. "We hit a lot of brick walls, but someone was there to help us out," says Yasue. "So I think that's a major thing, connecting to people. It's not just the technology and the engine."
And you can read about Luminous design for ease of development here now that the engine is mature and they've completed a game on it. It's a complete 180 compared to the FFXIII post-mortem talk about Crystal Tools I linked to earlier.
