The thing I don't like about numetal is this:
Take Atheist for example. I got Piece of Time long ago, and I listened to it while I drove. I liked it more and more and more. One time it just clicked and I was in love. I listened to it even more and it got better and better. It clicked even more today, and I listened to that album about four times today, i'll probably listen more.
That does not happen with numetal, numetal is like at first it can be catchy, and you might like it a bit. Then with each listen it just gets more boring.
I made generalasations, I am just talking about most numetal, I know there are exceptions, so don't jump on me for generalising.