I'm not asking for you to implement this, I'm offering to implement that feature on my own.
I'm software automation/integration engineer and would be happy to implement this feature on my spare time, for collection of 500 songs it would save the user 500 clicks.
As some songs are direct links to .psarc -files, it would save the user over 50% percent of clicking.
Which IMHO would be a quite sweet, I just re-downloaded my entire collection to my laptop which was quite a chore.
Perhaps the clicking part could be automated with selenium webdriver to have complete automation of re-downloading full collection with a single click.