When Hangul was invented, Korean was tonal and Hangul accounted for this with diacritics.

Apparently some dialects of Korean are still tonal.

https://autolingual.com/korean-tones/

Thai spoken language is the opposite extreme of German, vowels are the salient parts and consonants are often barely present and highly interchangeable. I don't know how the Thai written language works or how complex it is in comparison but I imagine it also wouldn't be a straightforward mapping. Quick lookup says it's tonal and analytic [idk what this is] like Chinese and Vietnamese.

But why? Vietnamese are doing just find with Latin alphabet with few extra characters (same as many Slavic languages). You don't need any special writing system to have tones in regular alphabet.

The same idea works tonemes distinguished by common graphical features as well.

> But Hangul is great, I wish Thailand would adopt it.

What a weird wish. Does Hangul even have ways to write the in-between consonants in Thai like dt or bp? Does Hangul even have the Thai vowel sound ื (which certainly has no unambiguous way to be written in English)? And then what about tones? Tones in Thai are not written explicitly, but computed based on a number of factors including character classes, length of vowel sound (does Hangul have a way to indicate short or long vowels?), end-of-syllable sound, and tone mark. If you wrote Thai in Hangul, how would you pay homage to loan words from Pali/Sanskrit? Again, just... what a weird wish!