I found CoX's enhancement system to be anything but simple. For one thing, it wasn't 6 items, it was up to six items per power, with what items a power could equip varying by power, and how much of a bonus the item gave varying by a) what aspect it enhanced, b) what type of item it was (training, DO, SO, Hammi-O), c) how many of them you equipped (ED diminishing returns), and d) level of the item relative to your current level. And that's not counting IOs and Incarnate junk!
What made CoX seem simple was that for most PvE content, you could get by without any enhancement at all. It might be slightly painful, but you could complete most missions with all your enhancements red or empty if you had to... and on a team you might not even notice immediately when your enhancements went red during a mission. If the game was less forgiving and you had to have nearly optimum enhancement in order to survive and defeat foes, the complexity of the trade-offs would have been much more apparent.