Drupal 8 introduced the use of Semantic Versioning, which practically means the use of three levels of version numbers. The current release is Drupal 8.1.8. While increments of the last number are done for bugfixes, the middle number is incremented when we add new features in a backwards compatible way. That allows us to add big new things to Drupal 8 while it is still compatible with all your themes and modules. We successfully added some new modules like BigPipe, Place Block, etc.

But how do we decide what will get in core? Should people come up with ideas, build them, and once they are done, they are either added in core or not? No. Looking for feedback at the end is a huge waste of time, because maybe the idea is not a good fit for core, or it clashes with another improvement in the works. But how would one go about getting feedback earlier?

We held two well attended core conversations at the last DrupalCon in New Orleans titled The potential in Drupal 8.x and how to realize it and Approaches for UX changes big and small both of which discussed a more agile approach to avoid wasting time.

The proposal is to separate the ideation and prototyping process from implementation. Within the implementation section the potential use of experimental modules helps with making the perfecting process more granular for modules. We are already actively using that approach for implementation. On the other hand the ideation process is still to be better defined. That is where we need your feedback now.

See https://www.drupal.org/node/2785735 for the issue to discuss this. Looking forward to your feedback there.