Examples of working links: http://link.springer.com/book/10.1007/978-1-4302-5927-5 http://link.springer.com/book/10.1007/978-1-4302-6131-5 http://link.springer.com/book/10.1007/978-1-4842-0100-8
The content identified by the original post were not open access; they were paid access (typically quite expensive) and published in 2004 or before.
I hope the zero cost downloads was not a glitch but a policy, and that Springer will make those older texts freely available again.
If I had to guess, I'd say a pretty good chunk of them already were on torrent sites or LibGen.
Examples of working links: http://link.springer.com/book/10.1007/978-1-4302-5927-5 http://link.springer.com/book/10.1007/978-1-4302-6131-5 http://link.springer.com/book/10.1007/978-1-4842-0100-8