...as opposed to a bear or other predator? Was there a specific defining characteristic of the wolf that made it necessary? Some behavior of wolves that Romulus and Remus took with them, that was required for their leadership? Pack mentality? Predatory? Etc?
The language you use about why a wolf was "chosen" implies that there was a conscious choice at the bedrock of the legend of Romulus and Remus. I'm not sure that was the case. Legends emerge more organically without a single author making conscious choices. That said, if the foundling brothers were to be raised by a wild beast, a canine at least as the sort of visible mammillary glands to make it a little more believable. Suckling from a bear might not be as easy - keeping in mind that I have attempted neither so I can't speak with authority. The main point here is that this is how the legend emerged more than how it was crafted.
I've heard that it might have been the case that they were raised by a prostitute. (lupa meant she-wolf and was slang for a whore.)
Is there any support for this?