Mo creatures is a good justification for the EE final armors
I dunno about you, but the combination of Swiftwolf's Rending Gale (flying) and Archangel's Smite (seeking arrow shotgun/machine gun) basically makes any and all mobs insignificant. And that's not even the highest tier stuff.
Thats my point. Whats the point of building even better weaponry when you can one-shoot pretty much everything with a god damned musket you can make with 4 Iron, 1 Flint, 3 sticks and a plank of wood?
The creepers need to stay out of your vision and wait around corners for you, and try and path to all your chests. Spiders need to get up to high places and pounce when you open or attack something. Zombies.....Need to be more. Many more. Skeletons, shoot arrows that can set block on fire and poison the player.
And creepers can ride spiders. That the type of hard your looking for?
The thing is, a lot of those mobs are actually pretty pathetic once you have a decent set of equipment. Creepers can be easily detected and avoided if you are both cautious and quick enough, Spiders are pretty easy to kill once the've pounced on you and can be prevented via a one block long outcroping on your roof, and Zombies are laughably easy to kill in the group sizes they are in now. The only one I'm scared of on that list is Skeletons, which have slain me on many occassions. However, thats more because of my strange and silly behavior which leads me to never making a Bow or Arrows for it. However, once pinned against a wall, Skeletons are easy, as you can just keep spamming attacks before they can hit you.
But yes, these mobs can be hard in some situations. But thats not my point. My point is that a lot of Mods, notoriously a lot of the ones in the Technic pack, add all kinds of super powerful weapons and Machines, but don't add proportionate Difficulty to challenge you. A little while into a game of Technic and you can just destory everything in the snap of a figure.