I have read this with interest. It is usual - at BA at least and I have no doubt that it is the same at American - that high heels have to be removed to avoid tearing a slide if one had to be deployed in an emergency. Comfortable shoes are sensible for in flight but should still be part of the uniform. Sneakers are not part of any uniform that I know of. This is American Airlines not Wendy's.

Uniform means just that. You don't get to pick bits of uniform. I might think that a Dark Blue skirt makes me look fat and that red suits me far better. No, sorry it's uniform and I have to accept that.

This is what happens when there is no onboard supervisor to inisit on service standards and procedure. Crew are there to be professional and to provide good service. If they can only provide this when clad in Crocs (yes I've seen that as well) then proabaly they should consider a career change.