> For the first year or so, pretty much everyone who's learning is going to need the romanization alongside / above the Hangul.
For folks who are learning Korean, hangul is maybe two days to get the basics and maybe a week or less to be able to get comfortable with it.
For super-casuals who just want a ballpark representation, you might be right, but I don’t think it’s reasonable to design around these super-casual folks — when they decide to get serious about learning Korean, Hangul will come quickly.
Hangul, as a phonetic representation, has about the same difficulty as learning hiragana, which takes about the same amount of time to learn.
Maybe if you are referring to older Korean texts that had Chinese characters in them, then I could understand.
> … It shows up in tools for Japanese, Chinese, Hebrew
Kanji (not a syllabary or alphabet), hanzi (not a syllabary or alphabet), and no vowels respectively.
These languages need some romanization support much more than Hangul, imho.