What problem does this address?

When creating a new block or plugin using the @create-block package we are limited to a certain number of parameters that we are prompted, it would be awesome if we could add more to the list, based on our custom configuration.

See: https://github.com/WordPress/gutenberg/blob/trunk/packages/create-block/lib/prompts.js

If this is already possible and I'm missing something, please let me know!

What is your proposed solution?

In this file: https://github.com/WordPress/gutenberg/blob/trunk/packages/create-block/lib/templates.js#L220

There is a getDefaultValues and getPrompts, maybe when someone defines params DefaultValues that are not predefined, we still prompt for them so they are later available in mustache when scaffolding the block?