MoO3 surely has its flaws, like the real time fights where the CPU of course has an edge, but it's the one and only 4X which makes the player feel like he's commanding a real huge galactic empire, not just a bunch of planets scattered here and there.
As a game progresses hundreds of planets and moons are colonized, those that first were barely unhabitable are now terraformed, crawling with people which will move by themselves and will populate other systems, maybe even within enemy's borders. Meanwhile those hundreds of planets are to be managed, the player can chose to automatize almost everything or take care of every single aspect, from the single building to the overall galaxy expenditures.
An excellent ship and fleet designer is just the icing.
Don't call this game "a spreadsheet" if it's too hard for you.