Japan doesnt build huge universes because creators own their works. there are rare exceptions, like Dragon Ball, or Go Nagai's connected universe, but Manga is the product of one person, or one creative team. US comics are the product of corporations. Corporations despise creativity because creation involves risk, and shareholders don't want risk. they want the stock prices to keep rising.
I can't believe you are actually defending Hollywood's current trend of sequels and remakes! you are probably the only person I have ever met who is super excited about sci fi and fantasy in movies just being the same shit with a different coat of paint. I guess you are stoked to see Ready Player One?
anyway, even if corporate cowardice weren't a terrible thing, you still have the vastly different business models separating cape comics from manga. Corporations want to sell whatever will move the most units for the lowest cost. Superman outsells anything else, so the corporation directs its employees to make more Superman stuff. And, when there are billions of dollars on the line, nobody wants to gamble on a new thing that might fail.
in Japan, individual artists compete for readership, so they have to balance what is popular against what will make a splash. They are beholden to no shareholder but the rent lady, and making it big doesn't mean a billion dollar payday, just being able to eat steak, rather than ramen.
tl;dr - japan doesn't do big universes because it cant, and its audience doesn't want it.