It's a matter of input output ratio; the great classic 4x games like MoO, MoM, Civ2 etc. all have a small amount of possible player inputs, but have a large number of game outputs. Mediocre 4x games have a large number of possible player inputs and a large number of game outputs, while the terrible bloated 4x monsters that tend to come out today have a large number of player inputs, but no matter how many sliders they give you to drag, no matter how many menu's and submenu's full of clickables are at the player's fingertips, the games tend to output in the same way every replay, leading to repetitive and boring games where the player does a lot of work for a stale and deja vu inducing reward.