Speaking as the person who implemented JSX support for TypeScript, I question the premise! JSX support (and implementation of React semantics for typechecking that JSX) was a very popular feature request. I can tell you just from how quickly people notice when something JSX-related changes in the nightly build that there are a lot of people using TypeScript with React. Also, since this seem to be a popular misconcept…
Javascript is a language and an ecosystem I really disliked until React and TypeScript came around and changed everything. We're making extensive use of JSX in our React app (https://github.com/hearthsim/joust / https://hsreplay.net/replay/ZXKe5VoqTzknRJNcPdTnYa) and it's really wonderful to both read and write.