Apple was first to lay claim to a successful online music store.
Apple was also first to develop a "good enough" protection system for the recording industry to be satisfied and allow online music stores.
There is a noticeable audio quality difference amongst the competing formats... WMA being inferior to Apple's AAC.
This article points out that Apple is the cause of a major standards problem amongst the digital music downloads right now.
No, Apple has 70%+ of ALL legal music downloads. They have 40% of worldwide music player sales. They were first. Others should standardize on Apple's format and if they can't [because Apple may not let them] - they need to come up with a different type of copy protection system.
Making a protected file is NOT the only way to secure a file.