• "We exist to provide value to our customers" - to make their lives better via lower prices and greater selection; all else is secondary
• Swim upstream, buck conventional wisdom
• Be in partnership with employees
• Work with passion, commitment, and enthusiasm
• Run lean
• Pursue ever-higher goals

I don't believe Wal-Mart has strayed in the context of their founding principles.  Some would argue they have strayed from their core purpose, which is "To give ordinary folk the same chance to buy the same things as rich people" when Wal-Mart eliminated the lay-away program.  I'm not sure I completely agree with this reasoning.  When lay-away was first created, obtaining credit was a much harder task.  In today's world, credit offers are a dime a dozen.  Of course, that is an entirely different subject with its own issues.

I believe the real question should be "Are Wal-Mart's founding principles leading to its downfall?".  In my opinion, Wal-Mart's principle of pursuing ever increasing goals coupled with its low cost focus has lead to some negative consequences.  While no one can fault any company for competing on the basis of lowest cost, the action in itself will force competitors out of business if they aren't able to respond.  Now add that to Wal-Mart's unyielding desire for growth, and you have a recipe for Wal-Mart's negative perception.

This negative perception calls into question the value Wal-Mart provides its customers and communities.  Providing value is a core concept for Wal-Mart.  All of Wal-Mart's business practices and policies are based on providing value.  Therefore, Wal-Mart cannot be successful unless it provides value to their customers.