Practical reasoning:
Which are the case where someone want to write down an url image? Are they more frequent than where one wants to view the image inline? I don't think so. So make sense priorize the inline usage with the simple syntax and use an alternative one (es. \
Counter argument: the simpler syntax works only it the url is a "speaking" one, so with a standard image extension. Some cdn don't output a similar permalink and so the regexp will skip and show them raw.
Several aspects to think about!