Glad to see you all pulled back from the brink of an all-out flame war. I was on the verge of closing the thread and making it disappear, but you seemed to get a grip on yourselves just in time.
Regarding the basic question, making a JD more aggressive would not in any way improve its suitability as a tankmate for a Midas cichlid. Given the size differential, the only thing that would result from a more aggressive JD would be a dead JD almost every time. If you had a different experience previously, that is definitely the exception and not the rule.
However, that does not mean you cannot have tankmates with a Midas in a 150g. That is what the larger schooling fish are made for (silver dollars, some of the bigger rainbows, etc.). Also the larger synodontis catfish and plecos. A school of silver dollars or rainbows (5+), a synodontis or two, and a pleco will fill the tank, and the Midas may well choose to leave them alone, as they do not really challenge him for control of his territory.
My Midas shares a 120g with five silver dollars, one synodontis ocellatus, and a marbled sailfin pleco. There have been no incidents in this tank, whereas when he was sharing a 400g with pacus, silver dollars, and a few other cichlids (synspila and one JD), there were always frayed fins (except on the JD, who wisely remained hidden most of the time).
, not as if there were any "Direct Personal Attacks" 
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You guys SLAY me! 