IMO there's no such thing as esoteric languages; it's just that some ideas catch on and some don't (or take longer). If C ideas had not caught on, today we'd all it an "esoteric" language.
Consider for example the Olympus language highlighted in the article. It is impractically verbose but is all the more amusing for it.
Other examples include languages made entirely from whitespace, one that I can't remember the name of that is designed to read like poetry in either German or English, and LOLCODE which is to be written in the style of lol cats memes.