More than that, every community from every instance can be synced but why they didn’t do that in first place? Probably because not overloading instances.

I presume so, it means smaller instances don't require databases the size of big ones for communities the majority of which they don't have any interest in.

Between LCB and New Communities it should be enough to get the word out as required.

Even though I’m partly doing it now, automating it is kinda daunting. I’m sure this tool will change in the future, but I would prefer to collect ideas rather than perform them in the short term :)

Yes, there's no rush - it's working well as it is, no need to make it over fancy and degrade the core functionality.