I do admit, I do like the Difficulty Modifiers in a game, because it's more fun and more challenging, so I've built some maps with some difficulty modifiers and it's more fun than in example of two robots wondering around without any clones. Sure you may dislike the map, because you've not experienced the modifier than what you think. You've got to admit, Games are fun when you try Difficulty modifiers than just shooting portals without any personal modifiers. I am more interested into more complex designs of a game that's rather difficult and I like the Complex maps that does are really hard personally. Other modifier types counts too.

Known Difficulty Modifiers I've made:
Diminishing Portals: The portals placed lasts for a short time.
Shadow Clones: Those clones really like to copy your every moves, and they're on the opposite side of the map.