Player choice is important. Every mod should have very detailed config options to allow any type of player to enjoy the mod. If it floats your boat to make a bucket of UU matter with 1 EU, you should have that option.
On a multiplayer server, it is different. If you are using an "overpowered" mod, cross-mods, exploits, etc, then it affects the other players on the server. For example: You are using a mod capable of duplicating blocks within a week of playtime. The other players are using mods that take a month to duplicate blocks. You have an enormous advantage in this situation. Your massive growth will have an impact on the world and server economy.
Yes? Obviously if your goal is to compete with other players than you have to use the most "op option." That doesn't mean other options shouldn't exist for people who don't give a damn about what their neighbor has.