Go to Admin->Languages and on lower left there is "language editor", select that. On the language editor page in the tree menu expand Local Resources->Admin->Users->App_LocalResources and then select "Profile.ascx". That will load the page where you can change the labels for profile properties such as name, etc. However, changing it will effect how it is displayed everywhere. So, someone who is viewing their profile will see the same message. I don't think there is a separate entry for "name" while registering and "name" after registering and viewing profile.
If it were up to me, I'd leave it as is because it is simple and concise and not confusing. If it could be made shorter I'd go for it, but I wouldn't make it longer. The "less is more" rule applies here imo. Also, if the length of the entry gets too long it could upset the layout of the page. I've noticed using too large of a font breaks the layout of the registration page so I assume too many characters could have a similar effect, but maybe not.
You can change and modify a lot of the basic language in the language editor, including the removal of your site admin email address which is exposed on the privacy and terms pages in their full glory for spam email harvesters... Every portal install I do, I go in here and modify the email address tokens to be either removed or replaced with directions to a contact page. I really wish they'd take care of this serious exposure problem sooner than later, I think it's been on the drawing board for a very very long time and there is already some kind of email cloaking script already in the core, it's just not been used or activated that I'm aware of.
Hope this helps,
Rick