When I'm viewing a user profile, it's more often than not to gauge this user within the community. How long they have been a member, how active they have been, when was their last activity and of course, what content are they contributing. This is accentuated when the user in question is a relatively new user. I would want to know this in order to make my response or comment more informative and to not be too harsh on inexperienced users.
One good measure I use to identify a new user is their join date. I would like to request that the "member for" field be added to the profile page for users on the mobile application just as it is when viewing the desktop version.
The "last seen" field would also be useful. It's useful to me on the desktop version to know more or less when/if to expect a response from a user after leaving them a comment/answer. It would useful on the mobile version for the same reasons.
I just realized that this information is available on the mobile version of the webiste. If it was decided that this information is important enough to also appear on the mobile web version, why not include it on the native mobile applications?