For people coming from Amsterdam it's not really convenient (timewise) to make a stop in the US. It's much more convenient to go with either Arke or Martinair, or go with KLM to Curacao and take a Insel or something similar to Aruba.
Seems that since KLM stopped flying to Aruba Martinair increased prices a little, as was mentioned already. Also, Arke seems to be full much faster than it was last year (speculation, I don't know for a fact)
Then again, if the only plane going to Aruba made a stopover on the North-pole I'd probably still go