I am much more interested in predictability in my code than I am about reordering arguments in mature codebases.
Lots of languages guarantee expression ordering to follow precedence and associativity rules, and I've never heard anyone say that it was a problem to refactor their code as a result.
Whereas I am 100% certain that there are lots of codebases where this is a ticking timebomb with developers unintentionally relying on the order their compiler decides to evaluate expressions in. And it will blow up when, not if, the GCC devs find some micro-optimization and decide to reverse things on them. And that's not just a problem for them, it's a problem for everyone who relies on their code.