It’s a fact, GUIDs are ugly.  So why use them for a common URI?  There are a number of reasons.

• First of all, RDF documents are meant to consumed by machines.  These have no problem processing GUIDs; they actually have an easier time because of the fixed length.
• Second, most existing descriptive URIs have an English bias.  This puts non-English speaking people at an unnecessary disadvantage.
• Third, a descriptive URI gives a false sense of being able to identify a subject by URI alone.  This is dangerous, since /George_Bush could refer to the 41st U.S. president, the 43rd U.S. president, or the guy down the street.  Various disambiguation techniques such as parenthetical suffixes have limited scope.
• Fourth, GUIDs don’t change.  It’s possible for a company or the George Bush down the street to experience a name change.  It would be unrealistic to expect all linked content to change associations to reflect this update, when a mere descriptive change would suffice.
• Finally, GUIDs can be generated offline and still be unique.  This allows asynchronous association to a common Open GUID that specifically identifies a subject.

For a truly global identifier, it is necessary to have multilingual descriptions to disambiguate a subject.  It is a straightforward task to develop tools that associate identifiers with local descriptions to help link content.