Because it's fucking epic and amazing fun! A true gem. Buy the DLCs when Steam Sales come up and it's actually not all that expensive, given AAA games are hitting £80 at new these days, getting a game that's been extensively fleshed out with DLC for around the same on sale is a bargain, and the game play runs incredibly deeply. It is one big management tapestry, optimisation of your planets, your sectors, your systems, your leadership, your scientists, your fleets etc etc etc - there are so many ways to play it. It's fucking amazing and the music kicks ass.