I think it's because of the talent behind the songs, and the lyrics. Some 电影院 use iconic 音乐 like Tchaikovsky's. He made some of the most 流行的 themes in all of classical music. They also have award-winning composers like Arnie Roth. Other times, they use teams of writers who have worked together before and can come together and make great songs (The Rock 'n Royals soundtrack).
There are also beats that make 你 want to sing and dance. 你 could listen to the 芭比娃娃 as Rapunzel 音乐 to relax, and the Princess & the Popstar 音乐 if 你 want to party! If 你 want something funny, listen to The 鼠, 大鼠 Song from 芭比娃娃 as the Island Princess. 音乐 for Christmas? Listen to the Perfect 圣诞节 and 圣诞节 Carol soundtracks. Then there's the lyrics. There are inspiring songs like "I'm On My Way", "Only A Breath Away" and "Making My Way". There's probably a 芭比娃娃 song to suit every mood, and I think that's why they're melodious and touching.