How many (modern, written) "ideographic languages" exist? I can think of two: Chinese and Japanese. Old Korean and Vietnamese used some Chinese characters, but the modern languages use none.

It is interesting to me when written Chinese and Japanese use commas. It is pretty much never required, but pure style. It does help to breakup a complex sentence, similar to phonetic languages.

Comma is required in modern Chinese. Nobody will bother reading your text if you don't at least put some of them in the right places...

(I don't know Japanese so I can't speak to that)

Nice post. Can you give a simple example sentence where it is required? (I believe you.) I studied Mandarin and Cantonese for a few years, but I never got the level where I thought commas were required.

Just a random text I had handy:

起初我見到一碟芽菜同西芹，以為佢上錯菜，用刀叉掘咗幾下，終於見到埋咗響底嘅叉燒。

Nobody writes it like this:

起初我見到一碟芽菜同西芹以為佢上錯菜用刀叉掘咗幾下終於見到埋咗響底嘅叉燒。

Can people parse the latter (with some difficulty)? Sure. The commas are not required to the extent that you can butcher the sentence even more without losing its essential meaning, but why stop there? You can remove even more stuff from it and still retain most of the meaning:

初我見碟芽菜同西芹以為上錯用刀叉掘幾下終見埋底嘅叉燒

But that's not how people write.

Japanese has a lot of “hint” on word (nouns) ending. And they use “full stop” plus one space to end a sentence as comma is not really needed in most cases. This is unlike chinese.

I’ve noticed in things translated from Japanese (video games, anime) there’s two features that seem constant and don’t seem to come from other languages. They seem to constantly say “in other words” and restate and clarify topics, and they put “quotation marks” around things that don’t seem to need quotation marks. I’ve always assumed these oddities would make more sense if I learned to speak or write Japanese.

    Japanese has a lot of “hint” on word (nouns) ending.

Can you give a simple example sentence to demonstrate your point? (I believe you.)

    This is unlike [C]hinese.

Can you give a simple example sentence to demonstrate your point? (I believe you.)

With the kind of mixed script used in Japan and that used to be used in Korea, they're not exactly necessary (still useful, but not necessary). Neither language uses prefixes much, so a sinograph is a pretty reliable indicator of the beginning of a word, followed by the inflection written out in a phonetic script like hiragana or hangeul. In Japanese's case, a switch from hiragana to katakana also indicates a word boundary and highlights that the word's likely a nonsinitic loan or the name of a plant or animal species or other technical term.

Say, for example:

"Korean people eat kimchi"

In Japanese/Korean, the structure would be:

Korean-person-topic marker-kimchi-object marker-eat-present tense.

In Japanese mixed script, that looks like:

韓国人はキムチを食べます。and would be read as "kankokujinwa kimuchiwo tabemasu".

Splitting it with spaces:

韓国人は キムチを 食べます。

The heftier kanji denoting "Korean person" and at the start of "eat" should be clear even to the untrained eye, while people who've studied the language can easily tell that キムチ is "kimuchi" written in katakana. The sentence is pretty easy to parse without spaces, at the cost of using one of the most insane writing systems in the world.

Now, what if we wrote the entire thing in hiragana instead?

かんこくじんはきむちをたべます。

... yyeaahh. Spaces. Please.

かんこくじんは きむちを たべます。There, much better, though almost no one fluent in Japanese has practice reading stuff like that.

In Korean, without spaces we'd have:

한국사람들은김치를먹어요. Again, similar problems. Korea has adopted spaces now that they don't use sinographs, so we'd have:

한국 사람들은 김치를 먹어요. (han'guk sa'ram'deul'eun kim'chi'reul mog'o'yo)

If we wrote "Korean person" with the same Sinitic loans in the Japanese sentence, we might get:

한국인들은 김치를 먹어요. (han'gug'in'deul'eun kim'chi'reul mog'o'yo)

Spaces clearly do help.