It's an interesting theory, but it's not so much the information density that bothers me, it's the explosion of graphics everywhere, which feels dumbed down to me in the other direction. Like on the rakuten page I linked, it's not good enough to list "3 awards" with bullet points and a small graphic, they need 2 screens worth of huge text next to trophies and stars. It's like they don't trust their customers to read something unless it's got giant text the size you'd find in books for literal toddlers and exciting or cutesy graphics to grab your attention. I get standing out in marketing, but it feels unfocused, like they couldn't decide on the couple things to highlight so you have to scroll past more than a dozen flashy banners to just click on the thing you're already on the page to buy.
On a separate somewhat related note, the literalness or overexplanation of the information also feels too much. Like they can't just have a simple title for a movie, manga, or webpage, they have to give a synopsis of the work in the title. Like how Pixar's Up becomes "Old Man Carl's Flying House". Or a site about the history of chocolate isn't just "History of chocolate and cocoa", it becomes "What's the history of chocolate? Also an explanation about the origins of cocoa". There's no extra info in that title, it's just longer.
I get that it's largely cultural, but if I could posit a theory it might just be like that because it's always been like that, rooted in how Japan is so slow to change. Ad company shacho rejects ads that don't barf colors because that's what he saw in ads when he was growing up. If I could make a somewhat skewed analogy, US TV shows through the 2000s had laugh tracks, but now if a show does that it feels lowbrow, almost bordering on insulting.
Guess you never ran across that kids book from the 70s. Apparently it also became a Seattle mascot. Anyway I never thought of it as a fancy word.
https://en.wikipedia.org/wiki/Wheedle