It is much more convenient and cleaner to use a single statement like
import java.awt.*;
than to import a bunch of individual classes
Forget about cluttered namespaces... And consider the poor soul who has to read and understand your code on GitHub, in vi, Notepad++, or some other non-IDE text editor.
That person has to painstakingly look up every token that comes from one of the wildcards against all the classes and references in each wildcarded scope... just to figure out what in the heck is going on.
If you're writing code for the compiler only - and you know what you're doing - I'm sure there's no problem with wildcards.
But if other people - including future you - want to quickly make sense of a particular code file on one reading, then explicit references help a lot.