Unironically agree with you.
It's not just something I feel about Omori but a lot of games of that style do it. Like Undertale, Lisa the Painful, ECT. The serious parts are much better than the silly parts, but Omori it's extra bad because the silly parts aren't even that good.
I think the devs felt compelled to add more content because their kickstarter goals and whatnot... Kickstarter goals are a big meme, as if you can just add or remove content from a game and have it still work no matter what.