I am not sure if we can compare them that easily in that regard since they have a different story behind it and thus maybe needed a different pacing
We absolutely can compare them that easily, because KH3 had a story that needed to be told and told it in a downright terrible way. This person told KH2s story using KH3's structure and devices to highlight this issue.
Also lets not forget that Roxas tutorial in KH3 was the whole of Hercules world. Only after that Kh3 appeared as logo exactly how Kh2 only appeared after Roxas went back with Sora. So in that way imo they are quite similiar just instead of a new none disney world our tutorial world was the huge olympus.
I know you have your opinion and are entitled to it, but regardless I think it's false to claim that the Roxas prologue was unnecessary and that it carried the same story weight as Olympus did. You cannot compare something that sets up practically all of the story for KH2, not to mention attaches you to a character and gives him some serious development, to a world that literally does nothing for the story except for showing maleficent and Pete who ultimately did nothing the whole game. Yes Roxas' story is long but it is *necessary* to KH2.
Radiant garden was in the end nothing but short scenes until the big battle. Heck we just meet the crew again, say to them that we will help with their huge problem but as soon as a new portal opens Sora leaves them behind. Their problem is not solved till later in the game. In KH3 we simply did not need such visits because we got our information another way. We still got cutscenes on Riku and Mickey and sometimes the other important people. Twilight town unlike Radiant garden was also a save world so its not like anyone needed help there.
Does worldbuilding and character interaction mean nothing to you? Sora knew the Committee, he visited Hollow Bastion, he was reacquainted with them, we got some really nice scenes where their friendship is cemented
("We may never meet again, but we'll never forget each other." "Is that supposed to be Leon?") we were introduced to Hollow Bastions conflict, but we were also introduced to the Organisation and ultimately Sora knew what the bigger fish was, and when he left HB it wasn't exactly falling apart was it?
When Sora was *told* to leave HB by Mickey to advance the plot he decided not to. That's another nice moment, plus, the battle of 1000 Heartless has easily one of the most badass moments (see my avi).
The fact that we don't need
such visits doesn't mean that they shouldn't be included. The Gummiphone was the worst thing to happen to KH3s plot and I will die on this hill. Instead of using all the characters and storylines at his disposal to give a bombastic finale Nomura decided to take the easy way out i.e streamline everything so that all we have is Disney worlds and the very very basic story beats that *everyone* knew would happen since DDD at least and BBS at most. That's not good storytelling.
I would not have anything against more worlds but for me at least they were not necessary. In the end would have more visits to twilight town for cutscenes really made the world better? When you have to land, loading screen, walk there, loading screen, see cutscene, loading screen, go back to map with a loading screen. All that for information that we simply got another way?
Like I said, just because something isn't necessary, doesn't mean it's not wanted. My post above showed what a completely "necessary" KH2 would look like, and honestly, it sucks ass. If that can't put KH3 into perspective for you then, eh. Whatever. You seemed easily satisfied by whatever the devs thought up and I didn't.
And yes, having a bigger twilight town act as a hub world would have made the game marginally better as they could probably do a lot more with it storywise. Hell, at this point, I'll take the mansion.
"All that for information that we simply got another way?"
Let's just make Kingdom Hearts wall-to-wall monologuing then shall we? If all we want is information. Gosh, it's like you didn't want to have all these opportunities like a data TT or the clock tower being somewhere explorable.