Gutenberg should aim to achieve feature parity with modern page builders. Their stellar success over the last few years is a clear indicator to what people expect from modern web creation platform. It's a clear win for all because plugin developers could focus on solving more specific problems.

Also, it would be great if the WordPress/Gutenberg UI/UX would be more cohesive and consistent. At the moment it seems as a collection of bits and pieces. As such it lacks the flow of modern design tools.