Not really.
The days of storing (and actually even having) hundreds and hundreds of gigs of MP3/flac etc are over. Streaming has pretty much made than unnecessary, and I actually still have hundreds of CDS for when I do want to use good headphones and enjoy the audio quality..
I use my 15" for audio recording, and installed about 150GB of various sample libraries I use, - so I'm good. I don't play games or store movies, and I certainly am not going back to non-retina, and I love the PCIe SSD speed.
Having just installed a non-PCIe SSD on my mini, - you can definitely tell the difference the speed makes..