I had more fun with the game when I had to work to get my materials. I enjoyed growing crops, building tree farms, mob farms, elaborate mine shafts, etc. That's half the fun for me. A creative server with limitless material spawning is basically akin to playing SimCity and hex editing your money to $99,999,999. It can still be fun to a degree, but it takes depth away from the game.
An economy system would only work if everyone using it doesn't use item spawners or WorldEdit. If you're that opposed to not using those though, I guess you could bar yourself from using the economy system or from giving anyone other than yourself materials or WorldEdit favors. If you did that, an economy system could still work I suppose.
I'm fine with creeper damage being disabled. No night while you're in the server is fine I guess. No mobs indoors is alright I guess.
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