AT&T's new OTA eMusic Mobile service results in $1.50 per song fee

Four mobile phones are listed to support the eMusic Mobile service, the Samsung Sync, Samsung A717, Samsung A727, and Nokia N75. You can listen to 30 second previews on your compatible phone and then download purchased music without connecting to a computer. Your purchase also results in a MP3 copy online that you can download to your PC and archive later. If you want more than 5 songs, then you can purchase Booster Packs at US$7.49 for 5 more songs. Keep in mind that previewing and downloading the music will consume wireless data so if you are not on an unlimited plan be careful how much you listen to on your device.

If you are interested in purchasing eMusic songs then why not just sign up directly with them and get the 25 free music downloads as well? I don't understand why anyone would want to use eMusic Mobile where the songs cost at least US$1.17 more per song. Am I missing something here or is this high premium cost just for the added convenience?