There's lots of ways to ensure security aside from at the protocol level, and DSA helps with compatibility, so this just seems like a bad idea to me. I don't think anybody was really accidentally using DSA not understanding the implications.
If you need this support, perhaps you should pay someone on the OpenSSH team (or an independent 3rd party) to support it. It's not free to keep code around, unfortunately; every bit adds a maintenance burden. It's an open source project, and no one is entitled to anything in particular.
