Today I was frustrated by this :
Maven 3.x no longer supports repositories using <layout>legacy</layout>. Users that need to access repositories created with Maven 1.x are advised to use a repository manager that is capable of providing a Maven 2.x compatible view of the legacy repository.
Even Maven's very own competitor, Ivy's ibiblio resolver supports Maven 1.0 legacy repositories.
Sonatype could simply change their suggestion to "Users that need to access repositories created with Maven 1.x are advised to use Apache Ivy."
I understand the need to force users to use the new technology, but not by disabling access to older technology without providing a practical alternative. At least wait for your competitors to stop supporting your legacy product before you yourself do it.
java.net Maven 1 repository contains artifacts that I need at times, now I have to hunt the artifacts or do workarounds that was simply solved using repository layout=legacy. Argh!