Mobile was a useful term when it was new and niche. You could use it in a conversation to narrow things down. Now it's so broad it's fast becoming meaningless.
I've long argued the same for the term "social media". Catchall terms breed ambiguity and lead to misunderstanding and poor execution. As a discipline matures, the language used to articulate its concepts must mature as well. It is time. We need to define and use more extensive vocabularies for "mobile" and "social media". Stay tuned.