Because Bash already has an expression parser/evaluator that it uses for this case, so now there isn't just one thing doing it, there are two, and you have to k

Because Bash already has an expression parser/evaluator that it uses for this case, so now there isn't just one thing doing it, there are two, and you have to know when they are used and when they aren't. Honestly the idea that a certain benign-looking syntax could (but maybe not!) spawn some external subprocess is terrifying to me, and I don't find it delightful at all.