I probably will always love MK. The reason MKD has worn on you so bad is probably all the Internet's fault!!! Back in the old days, you could go months without knowing all the fatalities and secrets, but now days, you learn everything within a couple days.
But I agree with most, there are some things that MKDA and MKD are missing.. I liked the old style digitized system and not the plastic mannequins that they have now.. Also, the newer systems seem a little clunkier and slower than they used to. I think that most of all I missed the way the characters jumped in the old system, when you jump now, it seems like you don't go very far.
One last thing I don't like.. New Characters that are rehashes of older characters. If you are going to use someone's move, you might as well have the person do it who originally did it.
However, overall I still love MK.