assumuing we have 5k incoming damage per second we end up with
1600) 5000*0.2475-(247/6+(.02*27000*3)/15+515/25)=1068 dps taken
1700) 5000*0.2397-(247/6+(.06*26000)/15)= 1053 dps taken
(assuming 1/2 90% accuracy, 1/2 100% accuracy, 1/2 energy/kinetic and 1/2 elemental/internal)
And therein lies the problem: there is no boss in current content which hits that hard. None. (I haven't finished parsing out NiM EC yet, but preliminary numbers still look well shy of NiM KP) In reality, the steady-state damage is about half that, with rare spikes that are much higher. If damage numbers were as high as you assume, then I fully agree that the self-heal is a poor substitute for more mitigation. Damage numbers are simply not that high (remember: wet noodle).
Your assumed balance of KE to IE damage is also quite far from the mark. Only 9.41% of damage is IE, which really isn't that much.
Finally, I'm not really following the expressions you give at various stat budgets. Could you explain your numbers a bit more? Also, your shield/absorb/defense ratios look quite off across the various stat budgets (my main sits at 1529 divided as 552/510/467 and is ideally balanced to within 0.0044%).