1. They were boring.
2. They were unrealistic.
3. They were unbalanced.
5. They required almost no strategy.
5. They made battles feel incomplete, and simplistic.
I'm just curious what difficulty level these people played on... Because they always make Civ IV sound so easy; "Make an invincible stack to conquer the world, pump out missionaries to make everybody love you".
I would consider myself rather good at the game, playing mostly at Immortal. While an early axeman rush often is profitable, but it will hurt the science output and if you don't have plenty of gold/gems/beavers, it will be very hard to support all units and cities, unless of course you raze everything, which will hurt you even more in the long run. It's not like you can pump out 30 axemen and steamroll the world.
I cannot stress this enough: Civilization is about strategic management, not battle tactics... Like the original Settlers! games... The battle outcome will mostly be based on how well your empire is doing and on which units you send in. When people complain about the "my stack is bigger than yours"-issue, they actually complain about the very concept of the game, which is to be more productive/efficiant than your opponents.
I've built missionaries occasionally to increase my income, but I'm finding it hard to believe that someone successfully manipulated the entire world to love them. Religion is only one thing that affects the diplomatic modifiers and many Civs don't even care about it. And there will always be Civs that don't like the Civics you have picked. And if you actually waste all your hammers on building missionaries, your Civ will probably be crippled in many ways, so even if you actually make everybody love you, it's not like your going to win the game by doing so... At least not after they tweaked the AP in a patch.
And all these "exploits", are actually what made Civ IV such a great game. Yes, building tons of Axemen can be deadly powerful. But building missionaries on the other hand, can boost your income and improve your relations with other leaders. Spamming cottages will secure your economy in the future, but specialist can give you a quick economy boost. Spies can instantly bring the cultural defenses.
There are TONS of really powerful tools, but you can't use them all at the same time. And the AI can use these tools as well. This leads to endless combinations and stories to tell.