While that model does help those who are developing libraries, it doesn't address the problems presented by open source applications. There's plenty of open source applications for which the charge-for-support and dual-licensing models don't create enough funds to assist development.

The other option would be open core (crippled open source). However, I dislike both, I still would prefer supported source as the goal is more clear.

I dislike the "open core" model as well. However, I don't see anything wrong with the copyleft, "release your source too or pay us" model. That provides very similar results: fellow developers can collaborate on the source, and companies building something they don't want to share can pay for an alternative license/exception so they don't have to. But instead of using a proprietary license to do so, that model uses a standard FOSS license, and works with the rest of the FOSS ecosystem.

Copyleft only affects changes to the original work. Usage with proprietary software is not affected.