I totally agree with all of you so far.
AtmosphereA cracktro, even if is just a legal production, should create an illegal atmosphere.
This means in the way it sounds or it is presented it should transmit the original
spirit ( i.e. underground, a criminal touch although very clever and kind of robin
hood like ). This could be done with a noisy ( but cool ) chiptune which kind of
symbolizes the underground way of creating music on the computer. Furthermore
maybe you remember the images of the cracktro by
UnitA 
The three men where you see no faces at all seems to be very mysterious.
Speaking of images, the logo seems to be an important part of the majority of
cracktros. Guess you cannot go wrong with a nicely designed 3D-Logo of the crew.
Design / FxAs you said before. A good text routine is very important. Furthermore it seems
that a good cracktro shows just a few oldschool effects ( maybe just one ) but
with in a newschool technique ( hardware accelerated and so on ).
I think rbraz links show perfectly what I mean.
TuneOld cracktros live from a noisy but catchy chiptune. I think this still counts for
modern cracktros. Maybe it is just my point of view. But I think even a modern
cracktro should have a chip-tune in it.