My hot take is that Motegi is more fun to drive than Monaco, Imola AND Mugello
Also it has more layouts than 2 of those tracks and a speedway oval around, unlike those 3
In Fact i had played once a game that had Motegi and Monaco on same game and Motegi was always fun to drive while Monaco was a boredom beacuse the track was TOO DAMN TIGHT TO PASS, the races always ended being a car train beacuse of the tightness
Monaco definitely sucks more than Motegi, but Motegi is probably the most boring of the Japanese tracks, most of it is just straightaway into hairpin/near hairpin into straightaway into hairpin/near hairpin. I imagine a lot of is just "we used to have it though!" nostalgia, and the only case I can really see for its return is that it has multiple layouts which is nice.
Okayama and Sportsland Sugo are both much better than Motegi (and Suzuka, and Fuji unless the game has good drafting) but sadly they have very small representation in games. Tsukuba gets a lot of love but personally I never got along with it, although the Forza series desperately needs good quality short tracks so I'd put it above Motegi too.
Tokyo from FM1 would be fantastic, maybe with a little bit of a rework with a few of those extra narrow alleys. I remember having some excellent races there. The long run into the tunnel before the hairpin was chaos sometimes with messy drivers, but was also a really interesting part of the track, both in public lobby with open builds and in spec racing.
I personally don't get the desire for Monaco in Forza, the only thing I can think of is people think the chaos would be funny in multiplayer which... it would be I guess... for the first 2 or 3 times, but not funny enough to be worth the time/space that could instead be used on a track that isn't trash.
Unfortunately the voting on the forum is basically just "how many casuals recognize the name of this track?" There are tons of fantastic gems on that list that I was actually surprised to see, however most have like 10 votes, meanwhile some Tilke parking lot has 100+ because people recognize it from F1.
Even if the threads for the tracks were better fleshed out with onboard videos and history and number of possible layouts, people probably still wouldn't read and just be like "oooh F1 track" and click on those. I hope they put more thought into their choices than just "I dunno this is what people voted for" but T10 hasn't shown much creativity or out of the box thinking when selecting tracks to add in the past.
To be fair, it's a tough job though and they kinda can't win. Personally, I love discovering and learning new tracks, and I'd love to see more obscure circuits that I can't just drive in every other game out there... But at the same time, when we like a racing game, we will inevitably think "man I wish my favorite track that is in all these other games was in this game too" and I feel like part of myself is missing if Nordschleife or Bathurst aren't in a game, even though I've driven them for thousands and thousands of laps in dozens of other titles.