I think you're also forgetting that a great many players don't want and don't like being in the bubble. There are thousands of explorers in Elite, people who enjoy being out in the black. Releasing a colonisation feature but limiting it only to players and player groups that want to stay in the bubble will alienate a huge volume of the player base as the feature to them, as it is to me, is utterly useless.
To give you one example...
- A player group that enjoys war with the Thargoids -

- A player group that has been set up to do piracy -

- A player group involved with the Fuel Rats -

There's also the point that there
are already colonies out in the black that didn't take 77 years to build. Colonia, Explorer's Anchorage, and the Heart and Soul nebulae are just a few.