> Typst has made some basic choices, which as someone who typsets a lot of math, makes it a no go.

For me, breaking from not just a 40-year-old history of mathematical typesetting but also from the American Mathematical Society recommendations is the dagger. Plus doubling work if you want to reuse what you wrote to render MathJax or KaTeX.

> $\alpha x$ is correct and $\alpha\beta$ is correct, but $\alphax$ is not.

Like you said, braces can be used so all of the following are valid: ${\alpha}x$, $\alpha{x}$ or the odd $\alpha{}x$.