Something meta here: Since CastleCMS is out I hear "when do we get this cool feature X into Plone core" (to some point valid vor PloneIntranet/Quaive).
In fact its first all about just doing it (I like the term DoOcracy here, even if its not very sharp and has many interpretations).
Write a PLIP, discuss it, get it approved, implement it yourself, find people (companies to send employees) to sprint on it (organize/support sprints), pay a designer/developer to implement, crowdsource money or development-time get it implemented, ...
Find like-minded to push the process together.
But whatever: you need to do it, like a seed in your garden needs lots of care to grow to a plant. Then the plant Plone can be harvested. And as it is software (=manifested/explicit knowledge) it gets more if its shared.
This is how Plone always worked. If we look at the current developments its still the main driver. Its how community driven FOSS works.
And even if a PLIP gets not approved: many features can be implemented just as add-ons.
Often its better to have just the generic hooks in core instead of an all-singing-all-dancing implementation - hey, we have the power of ZCA.