Keep in mind you don't start with a full homeworld, and the game now has Capitals ala Galciv... so if you want, you can build a research capital in your home system and fill up your homeworld with research centers...
Another balance issue... Metropolises seem overpowered compared to the regular facilities - they do TOO MUCH of everything for their low cost and small size! (20% the research/intel of a research facility, 33% the mining/farming/refining of the appropriate facilities, plus storage, all packed into a facility half the size and 40% the cost of a standard facility!
) Do they simply not advance as well with research? I haven't poked around in the data files so I don't know...